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Breast Cancer

This information should not be used for self-diagnosis or in place of a qualified physician’s care.

Reviewed December 2020

The basics

This section covers the basics of breast cancer: causes, prevention, screening, male breast cancer plus the signs and symptoms.

There is a small amount of fat between the surface skin and underlying muscle. The breast develops in this fatty layer on the front of the chest. Each breast consists of 15-20 lobes or segments. Lobes connect to ducts, and ducts lead to the nipple. 

Breast anatomy - female
Breast anatomy - male

The earlier a breast cancer is detected, the better the chance of curing it with treatment. 

If you find a lump, get a doctor’s evaluation. Breast lumps can be either malignant (cancerous) or non-malignant (benign): 

  • Not all lumps are cancer. Up to 90% of breast lumps are not cancer. 
  • Breast tenderness and generalized fullness before a period starts is common and is not a sign of cancer. 
  • Benign breast lumps may be solitary or multiple. Their cause is likely related to the normal cycle of hormonal effects on breast tissue. There is no way to prevent these changes.

What causes it and who gets it?

Some of the known risk factors for this cancer are listed below. Not all of the risk factors may cause this cancer, but they may be contributing factors. 

  • One woman in nine will develop breast cancer in her lifetime by the age of 80. The frequency of breast cancer increases with age. The numbers below are averages – some people are at higher risk than this, some are at lower risk. See risk factors and prevention information further down this page. 
  • Chances of getting breast cancer are: 
    • age 30 . . . . 0.44 % (or 1 in 227)
    • age 40 . . . . 1.47 % (or 1 in 68)
    • age 50 . . . . 2.38 % (or 1 in 42)
    • age 60 . . . . 3.56 % (or 1 in 28)
    • age 70 . . . . 3.82 % (or 1 in 26) 
      • Adapted from the NCI. Accessed Dec.16, 2016.  
  • Canadian First Nations and Inuit people have lower rates of breast cancer than other Canadians. 
  • Breast cancer is the most common type of cancer in women in B.C. In 2012 in British Columbia, 3198 women and 32 men were diagnosed with breast cancer.
  • Statistics 

Risk factors 

  • Risk increases with age - the risk of breast cancer doubles between ages 45 and 65. 
  • A previous diagnosis of breast cancer increases the risk of additional breast cancers. 
  • A family history of breast cancer, particularly breast cancer in a blood relative increases a person's risk. 
    • If the blood relative got breast cancer after menopause, the risk is two times greater than the average risk. 
      • Example (see table above): a 35-year-old has a 1 in 233 chance of breast cancer. The risk would be double, or a 2 in 233 chance of breast cancer if the person's mother got breast cancer after menopause.
    • If that relative had breast cancer diagnosed in one breast before menopause, the risk is three to five times greater than the risk to the general population. 
    • If the blood relative had cancer diagnosed in both breasts before menopause, the risk is nine times greater than the risk to the general population.

Other risk factors

  • Inherited changes in certain genes can increase the risk of breast cancer. People with changes (mutations) in the BRCA1 and BRCA2 genes have a very high lifetime risk of getting breast cancer, and a higher risk of developing breast cancer at a younger age. However, these mutations are rare. Only 5 to 10% of patients with breast cancer have mutations of these genes. There is more information on hereditary breast cancer and genetic testing from our Hereditary Cancer Program
    • Descendants of European (Ashkenazi) Jews have a higher than average chance of having a BRCA gene mutation.
    • Other rarer gene mutations can also increase the risk of breast cancer. 
  • People with a family history of cancer of the cervix, uterus or colon have a slightly increased risk. 
  • Estrogen exposure: longer lifetime exposure to estrogen increases the risk for breast cancers. Estrogen levels increase at puberty and decrease after menopause and during pregnancy. Factors that increase lifetime estrogen exposure are: 
     - Starting menstruation early (before age 12). 
     - Entering menopause at a later age (after age 55). 
     - Having a first pregnancy after age thirty (30) or never having a pregnancy. 
     - Using hormone replacement therapy (HRT) post-menopause.
  • Hormone replacement therapy (HRT), either estrogen alone, or estrogen combined with progestin increases the risk of breast cancer.
    • The research done by the Women's Health Initiative showed that taking HRT for more than 5 years (5-10 years) significantly increased the risk of breast cancer. 
    • HRT is now only suggested for patients with severe menopause symptoms, for as short a time as possible. You should be aware of the potential increased risk of breast cancer and factor this into their decision to take HRT. Decisions on HRT should be carefully discussed with a physician or oncologist.
    • If you had a previous breast cancer, you should not take HRT because of a possibility it may cause a relapse/return of the breast cancer. 
  • Drinking alcohol is consistently associated with an increased risk of breast cancer. 
  • In post-menopausal period, being overweight (Body Mass Index over 25) or obese (BMI over 30) increases the risk of breast cancer. This is probably because fat cells can make estrogen, so being overweight after menopause increases the body’s estrogen levels. Extra body fat may also hide a tumour and delay the discovery of a breast cancer. 
  • Radiation therapy to the chest (for example, for a cancer in childhood) can increase the risk of a later breast cancer.

Myths about breast cancer risk:

  • Breast implants do not increase the risk of breast cancer. However, persons with breast implants are in a higher risk category because mammograms can’t be performed as easily on them. You are strongly advised to have a pre-surgical mammogram as a baseline before getting implants. If you have implants, talk to your doctor about your options for screening for breast cancer. 
  • Oral Contraceptives – the Pill 
    • Most studies have shown no significant increased risk for breast cancer from oral contraceptive use.  The largest overall analyses show no significant increase in risk of breast cancer for persons who take oral contraceptives when compared to those who do not take oral contraceptives. 
    • Some studies have suggested a small increase in risk in persons who have mainly used older types of oral contraceptives, which contained more estrogen than those commonly used today. 
    • Other types of contraceptives that are estrogen/progesterone based (topical, injectable, patches, implants, etc.) have been less well-studied. The risk may be similar to oral contraceptives but this has not been proven. 
  • Underwire bras do not cause or increase the risk of breast cancer 
  • Mammograms do not cause or increase the risk of breast cancer 
  • An injury to the breast does not increase risk of developing cancer but sometimes can draw attention to a mass/lump already present. 
  • BC Cancer has examined the scientific literature on induced abortion and breast cancer risk, and has concluded that the weight of evidence does not show an increased risk.

Can I help to prevent it?

BC’s leading cancer organizations have joined forces to create Five Plus, a website that encourages everyone to take five steps that may help to prevent breast cancer, plus two actions for possible early detection:

  1. Maintain a healthy body weight
  2. Maintain an active lifestyle
  3. Limit your alcohol intake
  4. Breastfeed if possible
  5. Weigh the risks and benefits of hormone therapy for menopause symptoms
Be breast self-aware
Book a mammogram

Read about the top breast cancer prevention recommendations by visiting

Diet and nutrition

  • Eating healthy, nutritious foods, including plenty of fruits and vegetables, can reduce your cancer risk. Follow the recommendations in Canada's Food Guide and visit the BC Cancer page on Food Choices and Cancer Prevention.
  • You can also find detailed advice in the Canadian Cancer Society’s Eating well guidelines
  • Diets that include soy seem to have a small protection factor in preventing breast cancer. Soy products include soybeans, tofu, soymilk, edamame and miso.

Prophylactic mastectomy or oophorectomy

See the Treatment tab for this information. 

Hormone therapy  

Tamoxifen and Aromatase Inhibitors can be used as prevention in very high risk cases. See the Treatment tab for this information. 

Please speak to your physician or oncologist about prophylactic, or preventative, treatments. They are usually appropriate only in specific high risk situations.


Screening for cancer is looking for an early cancer when there are no symptoms or reason to believe there may be cancer present. This is different from diagnosis, which is looking for a suspected cancer found on a screening mammogram or a physical examination.

BC Cancer breast screening policy.


Mammograms are x-rays of the breasts. A screening mammogram looks for an unsuspected, hidden cancer in people who are healthy and who have never had breast cancer. 

BC Cancer Breast Screening encourages healthy people to have regular screening mammograms.  Visit their website for more information 

You can make an appointment for a free screening mammogram in B.C. once every 1-2 years without a doctor’s referral if you are aged 40+

To make an appointment for a screening mammogram call:

  • Lower Mainland: (604) 877-6187
  • B.C. Toll-free: 1-800-663-9203
If further tests are needed, BC Cancer Breast Screening has a Fast Track system in place and an appointment is scheduled as quickly as possible because we know waiting can be stressful. You'll be called directly by a diagnostic office nearest to you to arrange an appointment.

Magnetic resonance imaging (MRI)

MRI is used as a screening tool in people aged 30-65 with proven breast cancer genes.

Breast self-examination (BSE)

While there is no convincing evidence that breast self-examination reduces the likelihood of dying from breast cancer, BSE allows the person to become familiar with normal changes within their breasts over time. Many breast cancers are found by people examining their own breasts, particularly if they are not having regular screening mammograms. You should discuss the value of BSE with your doctor.

If you discover a breast abnormality you should talk to your primary health care provider to receive a referral for further diagnostic tests if needed.

Genetic (hereditary) testing

Breast cancer is the most common female cancer. In some families, more than one generation will have family members with breast cancers. However, only 5 -10% of all breast and ovarian cancers are related to inherited gene mutations (genes passed on from parents to children). There is an increased risk of several different kinds of cancer in an individual or family with mutations of the BRCA1 and BRCA2 genes. Most breast cancers that appear in families are due to mutations (changes) in those two genes. There are also other, rarer gene mutations in some families that can increase the risk of breast cancer. Individuals who have close blood relatives diagnosed with breast cancer may contact the Hereditary Cancer Program for more information.

Other screening methods in the news or discussed by patients and the public 

There has been considerable interest in methods of detecting (screening for) breast cancer that do not use x-rays (radiation). Such methods include thermography, ultrasound diaphonography, breast transillumination and magnetic resonance imaging (MRI), but none of these techniques have been proven to be as good as screening mammography and cannot be recommended at the present time. 

  • Ultrasound is not a good method to screen for cancers when there are no lumps or other symptoms. It can be used to determine if a known breast lump is a fluid-filled cyst or is solid. Cysts are essentially always benign. Solid masses often need biopsies to establish whether they are benign or cancer. 
  • Thermography measures heat patterns on the surface of the breast. It uses infrared detectors to record on film the hot and cold areas of the body. Cancers are thought to have an increased metabolism or increased blood supply, which will create ‘hot spots’. So far, it has not proven useful as a screening or diagnostic tool. This is at least partly because it only measures heat on the surface areas. 
  • Breast transillumination is the examination of breast tissue by a light source that penetrates the breast. Transmitted light is photographed by a video camera, which allows continuous display on a TV monitor and records the images. Different tissues have different patterns of light absorption - e.g., cysts will appear different from solid lumps. It has been found that some large cancers can be detected using this method. But the ability to identify very small, curable cancers that can often be seen with mammography has yet to be proven. At the present state of development, transillumination is not an effective tool for breast cancer screening. 
  • Screening MRI has been shown to be of value in individuals with proven BRCA mutations and a few other rare genetic syndromes. It has not been proven to be of value in screening people of average risk for breast cancer and is therefore not recommended as a standard screening tool.

Signs & symptoms

If you notice any of these signs, you should see your doctor for a breast examination:

  • A mass or a lump or a thickening or a change in your breast that is new or stays over time. 80% - 90% of breast lumps are not cancer.
  • A lump in your breast increases in the size, or your entire breast changes in size (gets visibly smaller or larger). Painful lumps are less likely to be cancer.
  • Your nipple begins to draw in.
  • There is dimpling or puckering of the skin of the breast.
  • There is a change in the contour (shape) of your breast.
  • You have bloody or watery nipple discharge.
  • Redness, scaling or inflammation of the nipple.
  • Your breast becomes red, swollen or hot.
  • A lump under your arm / in your armpit.

Male breast cancer

While very rare, breast cancer can develop in males. For every 100-150 women who get breast cancer, one (1) man will get breast cancer. Between 10 - 30 new cases of breast cancer in men are diagnosed each year in B.C.

Male breast cancer is very similar to female breast cancer, and they are treated essentially in the same way.

The main differences between male breast cancer and female breast cancer are:

  • Breast cancers in men are more often diagnosed at more advanced stages of disease (metastatic), probably because of patients ignoring lumps in their breast tissue. There may also be a lack of awareness that breast lumps in men may be cancerous.
  • A higher percentage of men than women have estrogen receptor positive (ER+) breast cancer.
  • Men who develop breast cancer are more likely to have inherited a gene mutation that increases their breast cancer risk than women with breast cancer.
  • Aromatase inhibitors are hormone pills that are used to treat women with ER+ breast cancer. It is not yet clear if aromatase inhibitors work well for male breast cancer.

Diagnosis & staging


The following are tests that may be used to diagnose this type of cancer. 

Up to 90% of breast lumps are benign (not cancer), but an ultrasound, a mammogram and sometimes a biopsy are needed to determine if they are malignant (cancerous). Many benign lumps change size during a menstrual cycle. Doctors may choose to observe a single lump or mass through a menstrual cycle to see if it becomes smaller or disappears, which would show that the lump is not cancer.


When a mass or lump is found through touch, or when a screening mammogram shows something unusual, the doctor usually orders a diagnostic mammogram. Diagnostic mammograms often involve more x-ray pictures than a screening mammogram.  Diagnostic mammography can help determine if a lump is probably benign or if a biopsy is necessary to make sure there is no cancer. A mammogram can also be used to guide a needle biopsy to the correct location (this is called “stereotactic core biopsy”)


When an abnormality is seen on a diagnostic mammogram, an ultrasound is used to determine if there is a mass (lump). Ultrasound can also tell if the mass is fluid filled (a benign cyst) or solid (a possible cancer). Cysts are filled with fluid and are essentially always benign. Solid lumps require biopsies to establish whether they are benign or cancer. Ultrasound is often used to guide the biopsy needle into the suspicious lump.


MRI’s full role in diagnosing breast cancer has not been defined yet. MRI can also be used to help aid the diagnosis of underlying cancer, when the patient has Paget’s disease, swollen lymph nodes under the arm, AND when both mammograms and ultrasound of the breast are negative but there is still a suspicion of cancer. A biopsy of a breast lump is sometimes done using MRI to guide the needle. A diagnostic MRI is different from a screening MRI.


The Pathology Report Patient Companion Guide was created to help breast cancer patients understand the pathology report and how the test results help guide treatment planning.  Feedback from patients, pathologists, physicians, surgeons and oncologists was used to make this guide clinically accurate and patient friendly. 

A biopsy is the removal of breast tissue for a pathologist to view under a microscope. There are several different types of biopsies.

  • Fine needle aspiration (FNA). A small needle is inserted into the lump to remove several cells. FNA can be done in a doctor’s office if the lump can be felt by the doctor or it may require the simultaneous use of an ultrasound, mammogram or MRI to guide the needle. If FNA confirms a cyst, usually no further biopsies are needed. If the fine needle aspiration confirms or is suspicious for a cancer, a further biopsy may be required. A negative finding will also usually be followed by a further biopsy. 
  • Core biopsies are usually done with the help of an ultrasound (most common), mammogram, or MRI. This ensures the needle is inserted into the area of concern.
  • Open or excisional biopsy. This is a surgical procedure to remove a lump. Occasionally this is done instead of a core biopsy, or after a fine needle or core biopsy, if a diagnosis is still uncertain. This is usually done using local anaesthetic (freezing the skin), but if necessary it can also be done under general anesthesia (putting a patient to sleep). This is almost always a day-care procedure and does not require overnight stay in hospital. If a lump is not easy to feel by hand, sometimes a mammogram or ultrasound is used to insert a wire into the lump before excisional biopsy, to guide the surgeon to the area of concern.

Hormone Receptor Testing / Human Epidermal Growth Factor Receptor 2 (HER2) Testing

This tissue removed at biopsy will be tested by pathologists to determine whether the cancer is sensitive to hormones. This will help determine treatment options.

For more information on tests used to diagnose cancer, see Recommended Websites - Screening and Diagnosis

Types & stages


Breast lumps are divided into malignant or non-malignant (benign) conditions.

Malignant tumours are non-invasive (in one spot, called “in situ”) or invasive (invading into the breast cancer fat around the ducts and lobules of the breast). It is very rare for in situ cancers to spread outside the breast. Invasive cancers can spread to the lymph nodes and other areas of the body.

Almost all malignant breast cancers are called adenocarcinomas, which mean these cancers are from the glandular parts of the breast. Depending on what glandular parts of the breast the cancer starts in (which is determined by looking at them under the microscope), they are called ductal carcinoma (75%), lobular carcinoma (15%), and medullary, tubular, scirrhous or other less common types.

Ductal Carcinoma In Situ (DCIS)

  • Breast cells are continually exposed to changing levels of hormones, which sometimes can cause cells inside the milk ducts to multiply. These multiplying cells result in a condition called intraductal hyperplasia. If the cells start to look abnormal, this is called "hyperplasia with atypia". The extra cells may block up the duct and begin to look like cancer cells. If that happens, the diagnosis becomes ductal carcinoma in situ (DCIS).

  • In DCIS, the cancer cells are confined to the milk ducts. DCIS is considered a pre-cancerous condition. As long as the cells remain inside the duct, DCIS is not invasive. If the cancer cells grow out of the ducts into the breast tissue surrounding the ducts, then it becomes an invasive cancer. DCIS is taken seriously, but it is very treatable and highly curable.

  • This condition is not usually found by physical examination. DCIS is most often detected by mammogram if the plugged ducts begin to accumulate calcium deposits.

  • Different types or growth patterns of ductal carcinoma in situ (DCIS) are recognizable under the microscope. Pathologists may give the DCIS additional descriptive names depending on how they appear under the microscope, such as ‘papillary, ‘cribriform’ and 'comedo’.

Lobular Carcinoma In Situ (LCIS)

  • LCIS, like DCIS, is a non-invasive condition, except the excess cells grow in the lobules of the breast.

  • LCIS is a marker for future breast cancer. If LCIS is found, this means that a breast cancer can develop in the future in either breast, not just where the LCIS was found. LCIS occurs less often than DCIS.

  • LCIS is considered a risk factor for future breast cancer. If the amount of LCIS is small, it may not mean a much higher risk of invasive breast cancer than for the average person. For people with a lot of LCIS, the risk is higher than average.

  • LCIS doesn’t show up reliably on mammography or ultrasound. It is often found when another lump or mammogram abnormality is being investigated by biopsy.

  • If LCIS is found, the aim of any treatment is to prevent breast cancer from occurring and to catch any developing cancers as early as possible. The options for patients include:

    • regular screening and followup.

    • tamoxifen, which can decrease the risk of invasive disease by approximately 50%.

    • the removal of both breasts, called prophylactic mastectomy. This is an extreme option and is only rarely recommended. There is more information about this option in the Treatment section.

Invasive Ductal and Lobular Carcinoma

  • These are the most common types of breast cancer. Invasive breast cancer means that cancer cells in the ducts or lobules of the breast have broken through the walls of these structures and invaded the surrounding cells.

  • If it appears to have started in the ducts, it is called a “ductal carcinoma” and “lobular carcinoma” started in the lobules.

Other invasive types of breast cancer

  • Other much less common microscopic types of breast cancer can also occur, such as medullary, tubular, scirrhous, and phylloides tumours.

Inflammatory carcinoma of the breast

  • This cancer shows up as an inflammation (redness, swelling) of the skin over the tumour. This special type of breast cancer is a fast-growing (aggressive) type of adenocarcinoma. It is very rare. (1% of breast cancers in B.C.)

Paget's disease

  • This cancer begins by looking like a skin disease, as dermatitis or reddening or scales on the nipple, which may be mistaken for eczema. The dermatitis is due to cancer cells invading the skin. The original tumour may not be felt on examination, and is frequently below the nipple. This is a very rare form of cancer (0.6% of breast cancers in B.C.)

Sarcomas or lymphomas of the breast

  • These are very rare cancers (0.5% of breast cancers in B.C.)


Staging describes the extent of a cancer. The TNM classification system is used as the standard around the world. In general, a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment. 

  • T describes the site and size of the main tumour (primary);

T1 = up to 2cm in size; T2 = 2.1 to 5cm in size; T3 = bigger than 5cm; T4 = any size but tumour is fixed/attached to either the muscle under the breast, breaks through the skin of the breast, both, or there is redness/swelling of the breast) 

  • N describes involvement of lymph nodes;

N0 = no underarm lymph nodes have cancer in them; N1 = 1 - 3 underarm lymph nodes have cancer in them; N2 = 4 - 9 underarm lymph nodes have cancer in them; N3 = 10 or more underarm lymph nodes have cancer in them, or other nearby lymph nodes have cancer in them. 

  • M relates to whether the cancer has spread elsewhere in the body (presence or absence of distant metastases).

M0 = no cancer spread beyond the breast or lymph nodes; M1 = cancer spread 

  • Stage 0 
    The tumour is non-invasive and often small. Discovered by mammography before a mass can be felt. In situ (pre/non-invasive) ductal or lobular cancer 

  • Stage I 
    The tumour is less than or equal to 2 cms in diameter and there is no spread to the lymph nodes under the arm or elsewhere (T1N0) 

  • Stage II 
    The tumour is larger than 2 cms but not more than 5 cms in diameter and/or involves lymph nodes under the arm. (T2N0; T1N1; T2N1) 

  • Stage III 
    The tumour is larger than 5 cms or there may be a lot of involvement of lymph nodes under the arm. However, there is no spread elsewhere in the body. (T1N2; T2N2; T3N0; T3N1; T3N2; T4N0; T4N1; T4N2; T4N3) 

  • Stage IV 
    The breast cancer has spread beyond the breast and area lymph nodes to another area of the body (for example bone or liver). (M1)



Cancer therapies can be highly individualized – your treatment may differ from what is described below.

Breast cancers are treated by surgery, radiation, chemotherapy or hormonal therapy. Almost always it’s a combination of these that is offered, depending on the individual situation. The choice of treatment depends on: type, size and location of the breast cancer; age and health of patient; known or possible spread to the lymph nodes in the underarm or elsewhere in the body; tumour receptor status for estrogen, HER2 and progesterone; and patient and physician preference of treatment. 

For early breast cancer that is contained to the breast and/or underarm lymph nodes, surgery is the most important component and is usually the first treatment. 

The need for radiation, chemotherapy and/or hormone therapy is generally decided based on the information found under the microscope, after examining the removed cancer. 

For breast cancers that have already spread to distant parts of the body, surgery may not always be part of the treatment.


Getting Ready for Breast Surgery - This booklet helps prepare patients for breast surgery at BC Cancer or Vancouver Hospital / UBC. Although most of the information is similar to breast surgery at other B.C. hospitals, please check with your surgeon or hospital for their information about getting ready for surgery. 

Surgery for invasive breast cancer includes removing the tumor from the breast and examining some of the lymph nodes from under the arm to determine if the cancer has spread. 

Surgery of the breast can be either a lumpectomy or mastectomy. 

Optimal surgery for ‘in situ’ breast cancer does not require sampling of the underarm lymph nodes, as this type of disease rarely spreads outside the breast. 

Surgery for the underarm nodes can be a ‘sentinel node biopsy’ or an ‘axillary dissection’, and sometimes both are needed. 


This is also called Segmental or Partial Mastectomy. This surgery removes the tumour and a small margin of the surrounding normal tissue. Because of this, it saves or ‘conserves’ most of the breast. Currently, approximately 1/2 - 3/4 of all breast cancers can be treated with this breast conserving surgery.

Sometimes a surgical margin may be too close to the cancer cells, and a further surgery is recommended to remove additional tissue in this area (a “re-excision”). Occasionally a mastectomy (removal of all the breast tissue) will be recommended after a lumpectomy, if more cancer is found than was expected. 

Lumpectomy is followed by radiation therapy to the breast to reduce the chance of the cancer coming back within the remaining breast tissue. Anyone who cannot have radiation, or does not want radiation, should have a mastectomy instead. 


This refers to a surgery where one whole breast is removed. There are several types of mastectomy described below. A lumpectomy is not always the safest or best surgery for breast cancer. Whether a mastectomy or lumpectomy is recommended depends on many factors, which are described in more detail below. 

  • Simple Mastectomy: In this procedure, all the breast tissue is removed, but no underarm lymph nodes are removed. This type of mastectomy may be used in the treatment of in situ disease. 
  • Modified Radical Mastectomy: In this procedure, all the breast tissue is removed, and lymph nodes under the arm are removed at the same time. 
  • Radical Mastectomy: In this procedure, all the breast tissue and underarm lymph nodes are removed, and the muscles of the chest wall underneath the breast are removed. Although this was the standard operation for breast cancer until 1970, it is rarely performed now, as this extensive surgery has not been shown to improve survival and is more disfiguring. 


Immediate or delayed breast reconstruction is frequently an option for patients following a mastectomy. With immediate reconstruction, a general surgeon performs the mastectomy and a plastic surgeon performs the first part of reconstruction during the same anaesthetic. Depending on what type of reconstruction is performed, further surgery may still be necessary later. With delayed reconstruction, all cosmetic reconstructive surgery is performed much later, after all cancer treatment is completed. For more information, see Breast Reconstruction and Prosthesis or Vancouver Coastal Health

Lymph Nodes

Lymph nodes are part of the lymphatic system, which is part of the immune system. The most common place for breast cancer to move (metastasize) to is to the lymph nodes under the arm. 

When breast cancer spreads only to the underarm lymph nodes, it is still a curable cancer. 

Because in situ cancer so rarely spreads outside the breast, underam lymph nodes are not usually removed when breast surgery is done for in situ cancer. 

During the surgery for invasive breast cancer, the surgeon usually takes out some underarm lymph nodes. A pathologist then separates out the lymph nodes from the remaining tissue and examines them under the microscope to see if there are any cancers cells inside any of them. There are two types of lymph node removal. 

  • Axillary dissectionThe surgeon removes all of the tissue under the arm below the axillary vein. 
  • Sentinel node biopsyFewer lymph nodes are removed from under the arm. The breast is injected with a dye or small amount of radioactive material before surgery, and this helps the surgeon identify the underarm lymph nodes most likely to contain cancer cells. These are removed, and if no cancer is seen by the pathologist under the microscope, no further underarm lymph node surgery is required. Only about 25% of invasive breast cancers have spread to the underarm lymph nodes, so the sentinel node biopsy allows fewer nodes to be removed. However, if cancer is detected in any of the sentinel nodes, then a second surgical procedure with an axillary dissection is usually recommended. Sometimes a sentinel node procedure is not done: when the likelihood of lymph nodes containing cancer is felt to be high, or the likelihood of accurately finding the sentinel lymph node is low. 

Examining lymph nodes under the microscope provides important information about the chance (risk) of a cancer coming back, and helps guide recommendations for treatment after surgery. 
Complications of lymph node removal from the underarm. 

Complications of lymph node removal from the underarm

The risk of these complications is lower with a sentinel node biopsy than with axillary dissection, which is why the sentinel node biopsy is preferred for most patients. 

When the normal drainage of lymph fluid from the arm and breast are disturbed by a sentinel node biopsy or axillary dissection, there is a risk of lymphedema, or swelling of the hand or arm. 

Difficulty raising the arm: Following underarm surgery, scarring occurs as part of the body’s natural healing process. This can create a pulling or sore sensation under the arm when trying to raise one’s hand above one’s head. It is important to practice this kind of arm movement early and regularly after surgery to minimize this problem. 

Numbness under the arm: Surgery to the underam often results in an unavoidable injury to a nerve that provides sensation to the skin under the upper arm. This usually leads to numbness in this area, which may be permanent or very slowly improve. 

Pain in the upper arm: This occasionally happens just below where the surgery was done, and improves with time. 

Exercise after surgery is very important to return the full use and range of motion of the arm and shoulder.

Choice of surgery

The choice of lumpectomy or mastectomy, and of sentinel node biopsy or axillary dissection, depends on many factors. These include: 

  • the size and location of the tumour relative to the size of the breast
  • medical fitness of the patient
  • the patient's own preference

In general, patients who are suitable for lumpectomy would have: 

  • a solitary breast cancer less than 4 cm in diameter
  • a large enough breast that removal of sufficient tissue would not leave a poor cosmetic result
  • a preference to preserve the breast
  • no reasons that make radiation after breast conserving surgery dangerous, impossible or impractical
In general, regardless of the breast surgery performed, the patient suitable for sentinel node biopsy has: 

  • A solitary cancer less than 2 cm in diameter 
  • No previous breast reduction surgery 
  • No previous surgery to the lymph nodes under the arm 
  • No obvious spread of cancer to underam lymph nodes prior to surgery 
  • Has not already had a mastectomy 

Prophylactic Mastectomy 

Prophylactic (preventive) mastectomy is the removal of one or both breasts (bilateral mastectomies) when there is no evidence of cancer in that breast. These are done very rarely. 

Surgery for existing breast cancers is more important than surgery to prevent possible future cancers. Sometimes a patient with breast cancer will ask for, or be recommended to have, a prophylactic mastectomy. Usually the prophylactic mastectomy will be done during breast cancer surgery on the affected breast.

Some patients without breast cancer who are considered to be at very high lifetime risk of developing breast cancer (for example, a 50% or higher risk) may choose to have both breasts removed even though no cancer has yet been diagnosed. 

A doctor may recommend that a patient have a prophylactic mastectomy if there is a strong suspicion of cancer developing in the opposite (contralateral) breast because of: 
  • a strong family history of breast or ovarian cancer or the patient has the BRCA gene. 
  • pre-invasive (in situ) or invasive lobular cancer in the opposite breast. 
The decision to have a prophylactic mastectomy should be made only after a thorough discussion between the patient and their doctor(s). 

There are two kinds of prophylactic mastectomies. Immediate or delayed reconstruction should be discussed with patients undergoing prophylactic mastectomy. 
  • In a total prophylactic mastectomy, the breast and nipples are removed, but not the lymph nodes. 
  • A subcutaneous prophylactic mastectomy preserves the nipple but leaves behind more breast tissue than a total mastectomy. Subcutaneous mastectomy is discouraged. 
100% of the breast tissue is not removed during a total prophylactic mastectomy; a small amount of breast glandular tissue probably remains against the chest muscles or attached to the skin, even after bilateral mastectomy. 

Every patient at high risk for breast cancer should be offered psychological and genetic counselling. The risk of developing breast cancer can be estimated, fully discussed and understood. Information about reconstruction alternatives should be provided. Patients with a very strong family history of breast cancer who are considering prophylactic mastectomy can be referred to the Hereditary Cancer Program for counselling and referral for testing, if testing criteria are met.

Radiation Therapy

Radiation therapy can also be called radiotherapy, irradiation or just radiation. The health care providers may also say that they are going to radiate the tumour. 

This treatment is designed to stop the growth of cancer cells while trying to preserve the normal tissue. 

The most common kind of radiotherapy in B.C. is called external beam radiotherapy and it uses a large machine, like an x-ray machine, to deliver radiation into specific areas of the body at a specific angle and depth. 

It is painless, much like having a chest x-ray. The patient lies flat on a table and the machine is lined up to treat the part of the body that the doctor feels is necessary. 

Since these machines are large, expensive and highly specialized, the only place in British Columbia where radiation treatment can be obtained is at BC Cancer clinics. 

Also used in B.C. (in clinical trials only) is partial breast radiotherapy. This is available at all BCCA Centres.
Radiation treats the breast and sometimes the nodal areas (the lymph nodes nearest to the tumour). 

Radiation therapy is used in several different circumstances: 
  • After a lumpectomy (segmental mastectomy), radiation to the breast greatly reduces the risk of cancer re-growing in that breast. In order to minimize side effects, the treatments are usually given over a series of treatments on weekdays for 3.5 - 6 weeks. 
  • It is used after a total mastectomy if the doctors think that there is a high risk of cancer regrowth on the chest wall. This happens when there are large cancers, or if there are many positive lymph nodes found during the surgery. 
  • Sometimes radiation is used before surgery, if the doctors feel that the cancer cannot be safely removed. Often it can shrink the cancer so that surgery can happen after the radiation.
  • If the cancer comes back, radiation is often useful to relieve pain, bleeding or certain other problems. 
Side effects of radiation therapy can be very different depending upon which part of the body is treated, and by the patient’s response to the dose they are given. When treating the breast area the usual side effects are: 
  • Some redness, discomfort and dryness of the skin. 
  • Possibly a sore throat. 
  • Fatigue. 
After treatment, protect the radiated area from the sun, especially in the first year. 

Instructions as to what side effects to expect and how to minimize them are given to each patient before they start treatment. 
Available treatments for any possible side effects will also be discussed.


Chemotherapy is the use of drugs to kill cancer cells. 

Chemotherapy can be given as tablets or injections. 

Chemotherapy is used in both pre- and post-menopausal patients. 

Many drugs have been shown to be effective in the treatment of breast cancer.

In general, chemotherapy is used in two situations: 
  • To kill cancer cells that might still remain after the surgery and/or radiation, when the cancer seems to be confined to the breast and/or lymph nodes under the arm. This is called adjuvant therapy. 
  • If cancer shows up elsewhere in the body, or comes back after treatment is over (recurs), then a treatment which can go throughout the whole body (systemic) is needed. Recurrent breast cancer at this time is treatable, but not curable. Each patient’s situation is different. The choice of when to start chemotherapy, what drugs to use and what side effects to expect, needs to be discussed between the patient and her doctor. 

Side effects

There are many different types of drugs, each with its own actions and side effects. Not everyone gets all these side effects. The usual side effects are: 
  • some nausea
  • occasional vomiting. The majority of patients do not vomit when given newer anti-nausea medications. 
  • fatigue
  • immune system and infections. Drugs can affect the blood producing bone marrow, which lowers "white blood cell" counts. Patients with low white blood cell counts have an increased risk of infection.
  • hair loss does not always happen, and depends on the drug and the amount of the dose
  • some patients' periods may stop temporarily or permanently (menopause)
  • occasionally, people get mouth sores. Talk to your oncologist about any mouth sores. There is a prescription mouthwash available that will help

Hormone Therapy 

Like normal breast tissue, some breast cancers can be stimulated to grow by hormones (estrogen and progesterone). These are called estrogen receptor positive (ER+) or progesterone receptor positive (PR+). If the tumour cells do not respond to the hormones, they are referred to as estrogen receptor negative (ER-) and progesterone receptor negative (PR-). 

It has been found that the growth of ER+ and PR+ breast cancers can be stopped in: 
  • post-menopausal patients by interfering with the low levels of estrogen that exist. 
  • pre-menopausal patients by stopping the ovaries from working, or by the use of anti-estrogen drugs. 
Hormone therapies are almost always used once the initial treatments are over.
Currently at BC Cancer, we recommend the use of tamoxifen for premenopausal patients, and tamoxifen followed by an aromatase inhibitor (AI) for postmenopausal patients. The length of time the patient will spend first on tamoxifen and then the AI is dependent on their individual circumstances, such as menopausal status. 

More information about specific drugs used for hormonal cancer treatment can be found in our Cancer Drug Manual ©.

In premenopausal patients whose ovaries are still working, tamoxifen is the preferred option, but sometimes ovarian ablation is used. Permanent and temporary options include: 
  • removing the ovaries surgically. 
  • giving a one-week course of radiation, which destroys the ability of the ovaries to function. 
  • Medications that can cause temporary menopause have been shown to be effective. 


Guidelines for follow-up after treatment are covered on our website. 

Follow-up Program after Breast Cancer Treatments pamphlet is available here as a PDF file for reading or printing:

You will be returned to the care of your family doctor or specialist for regular follow-up. If you do not have a family physician, please discuss this with your BC Cancer oncologist or nurse.

Follow-up testing is based on your type of cancer and your individual circumstances.

Life after Cancer focuses on the issues that cancer survivors can face.
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