Published: Thursday, May 03, 2007
1. Anatomy and function of the breast
Breast tissue extends from the clavicle to almost the middle of the sternum, into the axilla as the axillary tail.1, 2 The average breast measures 10-12 cm in diameter, and its average thickness centrally is 5 to 7 cm. Its three major structures are: skin, subcutaneous tissue, and breast tissue (parenchyma and stroma).
The parenchyma is divided into 15 to 20 segments that converge at the nipple. The collecting ducts that drain each segment are 2 mm in diameter, with subareolar lactiferous sinuses of 5 to 8 mm in diameter. Approximately 10 major collecting milk ducts open at the nipple. Each duct drains a lobe (called lobules or mild glands) made up of 10 to 100 alveoli. The stroma and subcutaneous tissue of the breast contain fat, connective tissue, blood vessels, nerves and lymphatics.2 The normal “lumps” that can be felt in the breast are a combination of the milk glands, ducts, and fat in the breast.1
The skin of the breast is thin and contains hair follicles, sebaceous glands, and sweat glands. At the perimeter of the areola are the openings of Montgomery Glands, which are large sebaceous glands capable of secreting milk. The breast is enveloped by fascia, with the undersurface lying on the deep pectoral fascia which covers the pectoralis and serratus muscles. Connecting the two fascial layers are fibrous bands (Cooper suspensory ligaments) that represent the "natural" means of support of the breast.2 With age, these ligaments tend to stretch and the normal breast begins to sag.1
The proportion of milk glands, ducts and fat in the breast changes as a woman grows older. During puberty, and as the breast develops, it consists mainly of ducts. In a 20-year-old woman, most of the breast is made up of milk glands. During pregnancy and breastfeeding, the glandular content of the breast increases dramatically as the breast prepares to produce milk. Male breast tissue is made up mostly of milk ducts.1
The fat content of the breast increases with age, especially after menopause. In an elderly woman, almost all the breast is fatty tissue. Hormones taken after menopause tend to maintain the glandular tissue and delay the normal fatty replacement.1
The main groups of lymph nodes that drain the breast are located just above the axilla (apical), above the clavicle (supraclavicular), and along the sternum (internal mammary). There are about 30 lymph nodes in each axilla, but the number varies for each person. Level I lymph nodes lie lateral to the lateral border of the pectoralis minor muscle, level II nodes lie behind the pectoralis minor muscle, and level III nodes are located medial to the medial border of the pectoralis minor muscle. These levels can be determined accurately only by marking them with tags at the time of surgery.2
Almost all lymphatic vessels in the breast connect to axillary lymph nodes, but some connect to internal mammary nodes near the sternum or supraclavicular or infraclavicular nodes near the clavicle.1 Approximately 3% of the lymph from the breast is estimated to flow to the internal mammary chain, whereas 97% flows to the axillary lymph nodes.2
Many nerves pass through the breast to the skin and to the nipple. In addition, the intercostal-brachial nerves come from the area between the ribs, through the axilla and reach to the underside or back of the upper arm. These nerves are often stretched or cut during surgery.1
Tables 1 and 2 below provide images of the basic structure of the breast and axillary nodes.
| Table 1. Breast Anatomy |
Breast profile:
A: ducts
B: lobules
C: dilated section of duct to hold milk
D: nipple
E: fat
F: pectoralis major muscle
G: chest wall/rib cage
Enlargement:
A: normal duct cells
B: basement membrane
C: lumen (centre of duct) |
 |
Table content sourced with permission from www.breastcancer.org
| Table 2. Axillary Lymph Nodes |
Lymph node areas adjacent to breast area.
A: pectoralis major muscle
B: axillary lymph nodes: levels I
C: axillary lymph nodes: levels II
D: axillary lymph nodes: levels III
E: supraclavicular lymph nodes
F: internal mammary lymph nodes |
 |
Table content sourced with permission from www.breastcancer.org
Estrogen and progesterone play important roles in the development of female breasts, body shape and regulation of the menstrual cycle. Before menopause, estrogen is made primarily by the ovaries. The pituitary gland releases hormones (LH and FSH) that control ovulation, the menstrual cycle and the production of estrogen in the ovaries. Pituitary gland hormones are released based on the level of estrogen in the blood. When the estrogen level goes down FSH is released to stimulate the ovaries. Pituitary hormones are also released at different times during the menstrual cycle.3
After menopause a woman still makes estrogen but the levels of estrogen are significantly lower than before menopause. Estrogen is made by the body by a complicated process which involves the adrenal glands, their production of cholesterol, and its eventual change into estrogen. The last enzyme involved in this long process of converting cholesterol to estrogen is called aromatase. The aromatase enzyme is found in large number of tissues in the body including fat, muscle, liver, breast and breast cancer cells.4
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2. Definition of breast health
Breast health means more than the absence of disease. It is based on the idea that women can make healthy decisions about their lifestyles, nutrition, fitness, and use of medications or other substances [to help keep their breasts healthy]. Heredity, age, and general health problems may also affect the health of a woman's breasts.5
3. The three-pronged approach to early detection of breast cancer
The three-pronged approach refers to:
- screening mammography beginning at age 40;
- clinical breast examination by a trained health professional at least every two years; and
- monthly breast self-examination (BSE) starting at age 20 to learn what's normal for your breasts so that any change will be noticed.6
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4. Incidence and survival rates for breast cancer in Canada and British Columbia
| 2003 |
Canada |
British Columbia |
| Number of new cases (women) |
21, 000 |
2,471 |
| Number of new cases (men) |
140 |
23 |
| Mortality - men |
40 |
3 |
| Mortality - women |
5,300 |
610 |
- One in nine women is expected to develop breast cancer during her lifetime. One in 27 will die of it
- Since 1994, death rates for breast cancer have been declining steadily 7
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5. Risk factors for breast cancer
Strong risk factors (risk greater than four times normal):
- Family history of breast cancer - particularly in a mother, sister, or daughter
- If blood relative is pre-menopausal and has bilateral breast cancer - risk is nine-fold
- If blood relative is pre-menopausal and has uni-lateral breast cancer - risk is three-five fold
- If blood relative is post-menopausal and has breast cancer - risk is two-fold
- Evidence of susceptibility gene BRCA1/ BRCA2
- Personal history of lobular carcinoma in situ
- Breast atypical hyperplasia
- Mammographic density occupying > 75% of the breast volume
Moderate risk factors (risk between two to four times normal):
- Increasing age (risk doubles between ages 40 and 50 and doubles again at age 70)
- Previous breast biopsy showing abnormal cells (atypia) or excessive accumulation of cells (hyperplasia)
- North American and northern European residence
- Family history of premenopausal breast cancer
- Personal history of breast cancer
- Breast hyperplasia without atypia
- Mammographic density occupying > 50% of the breast volume
Weak risk factors (risk between one to two times normal):
- Post-menopausal estrogen: women who have taken post-menopausal hormones for longer than seven to 15 years have an approximate 1.5-fold increased risk. Oral contraceptive use is not associated with increased risk of breast cancer, although it may reduce risk for ovarian and uterine cancer
- Onset of menses before the age of 12
- Cessation of menses after the age of 54
- Obesity and increased BMI in post-menopausal women
- Moderate to heavy alcohol consumption (more than three drinks or six glasses of wine per week)
- Dietary factors: the role of diet in affecting the risk of breast cancer is still inconclusive, but there are several large studies underway now to examine the importance of dietary fat
- Repeated radiation from x-rays in women younger than 20
- Family history of postmenopausal breast cancer, except if associated with male breast cancer or bilateral disease
- High socioeconomic status
- Older than 30 years old at the birth of the first child or no full-term pregnancies (delivery of first child before age 20 provides a modest protection and breastfeeding may decrease risk by a small amount) 8, 9
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6. What patients can do to decrease their risk of developing breast cancer
- Regular exercise (four hours or more per week)
- Reducing personal levels of stress - may have substantial health benefits, but may not affect cancer risk
- Do not start or stop smoking - will have substantial health benefits, but will not affect breast cancer risk
- Eat a healthy diet
- Reduce the amount of dietary fat to between 20-30% of the total calorie intake
- Increase the amount of vitamin A through eating more green and yellow vegetables
- Increase dietary fibre
- Limit alcohol to no more than three drinks or six glasses of wine per week
- Limit postmenopausal estrogen use to less than ten years where feasible
- For those at very high risk of developing breast cancer, consider tamoxifen for preventative use or prophylactic mastectomies 10
7. Eligibility criteria for screening mammography as outlined by the Screening Mammography Program of BC (SMPBC)
- B.C. resident 40 to 79 years of age (after age 79, a doctor's referral is required)
- Have no breast changes (e.g. new lumps, thickening or discharge)
- Can provide the name of a doctor to receive the results
- Have not had a mammogram within 12 months
- Have not had breast cancer
- Do not have breast implants
- Are not pregnant or breast feeding
A doctor's referral is not required for women aged 40-79 who meet the above criteria. Screening mammograms can be arranged with a doctor's referral each time in the following cases:
- Women age < 40 with a strong family history of breast cancer (i.e. two or more family members)
- Women who had radiation for Hodgkin's disease or other childhood cancers, particularly if the radiation occurred in teens or early 20s, should have annual mammography beginning ten years after diagnosis or at age 40 years, whichever comes first
- Women over 79 years who are in good health 11
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8. How breast self-examination (BSE) is performed
See the Breast Self-Examination website to learn how to perform BSE.
9. Why BSE is considered controversial
The Canadian Task Force on the Periodic Health Examination has reviewed the practice of BSE as a screening tool for breast cancer. There are no data showing that the practice of BSE results in the lowering of mortality due to breast cancer. The task force has therefore concluded that there is insufficient evidence to recommend practicing BSE to detect breast cancer. There are concerns that a large number of unnecessary biopsies and investigations are done for benign lumps and that this is of concern for women.
However, regular BSE allows a woman to become familiar with the normal changes within her breasts over time. While most changes are not cancerous, they should be investigated. In conjunction with physician examination, ultrasound and mammogram, many changes found on BSE can be diagnosed without an invasive biopsy.12
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10. Where patients can learn BSE in B.C.
Women can be taught proper breast self-exam technique by their physician or other health care providers. As well, breast self examination teaching clinics are held by trained volunteers at the:
- Breast Health Centre in Victoria: (250) 727.4467
- Comox Valley Nursing Centre: (250) 338.1711
- Pender Harbour Health Centre: (604) 883.2764
11. How nurses can promote good breast health practices in their communities
Nurses can promote good breast health practices in their community by:
- sharing accurate information on breast health and early detection;
- dispelling myths about early detection techniques and causes of breast cancer;
- encouraging eligible women to participate in screening mammography programs; and
- teaching proper breast self-exam techniques to their patients and members of their community.
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12. Resources available on breast health
REFERENCES
1. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.24-29.
2. Harris JR, Lippman ME, Morrow M, Osbourne CK. Diseases of the breast. 3rd ed. Philadelphia, PA. Lippincott Williams & Wilkins; 2004, pg.3-8.
3. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.165.
4. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.166-67
5. Copyright © 2006 BC Women's Hospital & Health Centre. All rights reserved. Terms of Use/ Copyright.
6. Canadian Cancer Society (http://www.cancer.ca). Narberth (PA): breastcancer.org; c2000-06. (cited Oct 18, 2006). Available from: http://www.cancer.ca/ccs/survey/P5Frames.asp?source=http%3A%2F%2Fwww%2Ecancer%2Eca%2Fccs%2Finternet%2Ffrontdoor%2F0%2C%2C3172%5F%5F%5FlangId%2Den%2C00%2Ehtml&site=1&lang=EN&log=197777
7. Canadian Cancer Society (http://www.cancer.ca). 2006 Canadian Cancer Society. All rights reserved.(cited Oct 18, 2006). Available from: http://www.cancer.ca/ccs/survey/P5Frames.asp?source=http%3A%2F%2Fwww%2Ecancer%2Eca%2Fccs%2Finternet%2Ffrontdoor%2F0%2C%2C3172%5F%5F%5FlangId%2Den%2C00%2Ehtml&site=1&lang=EN&log=197777
8. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.12-17.
9. BC Cancer Agency (http://www.bccancer.bc.ca). Vancouver (BC): 2006. (cited Oct 18, 2006). Available from: http://www.bccancer.bc.ca/PPI/TypesofCancer/Breast/Prevention.htm
10. Olivotto I, Gelmon K, McCready D, Pritchard K, Kuusk U. Intelligent patient guide to breast cancer. 4th ed. Edwards C, editor.Vancouver (BC): Intelligent Patient Guide Limited; 2006, pg.18-21.
11. BC Cancer Agency (http://www.bccancer.bc.ca). Vancouver (BC): 2006. (cited Oct 18, 2006). Available from: http://www.bccancer.bc.ca/PPI/Screening/Breast/default.htm
12. Baxter N with the Canadian Task Force on Preventive Health Care. Preventive health care, 2001 update: Should women be routinely taught breast self-examination to screen for breast cancer? CMAJ 2001; 164(13):1837-46.