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Breast Density

Please find information about BC's recent announcement to report breast density results below. 

  • Starting October 15, 2018 the BC Cancer Breast Screening Program will provide breast density scores with screening mammogram results to both providers and screening program clients.
  • The breast screening policy has not changed for women with dense breasts. The recommendations for screening mammography are exactly the same for women with dense breasts as for the rest of the eligible population. Women 40-74 years old with a family history should have annual screening mammograms. Women without a family history should have a screening mammogram every two years.
  • Breast density is provided to facilitate discussion between providers and women of related breast cancer risk and mammography limitations, and overall breast cancer risk assessment.
  • Mammography is still the best overall breast cancer screening test for asymptomatic women. It is able to detect many breast cancers before symptoms occur, even in women with the densest breasts.


  • Breast density is graded by the radiologist during the reporting of the mammogram. In BC, breast
    density is measured using the Breast Imaging Reporting and Data System (BIRADS) which
    includes a four-point density scale (A, B, C and D). These categories are listed in order of
    increasing density, with a BIRADS A category being the least dense category (mostly fatty tissue)
    and a BIRADS D category being the most dense (highest proportion of non-fatty tissue).
  • Breast density is common and breasts tend to become less dense as women age. Most women
    fall in the middle two density categories. A woman’s breast density score may change from
    screen to screen, because the amount of dense tissue may change and because the assessment
    is qualitative.
  • The sensitivity of mammography is reduced as background breast density increases. Therefore it
    is important to investigate all breast changes, even if a mammogram is normal.
  • Breast density is a risk factor for developing breast cancer, although having even the highest breast density does not mean that breast cancer is certain. The other risk is that breast density may make it more difficult to find signs of breast cancer on a screening mammogram, which is called “masking”.
  • Breast density is one of multiple risk factors. Increasing age, for example, is another risk factor and one that affects all women. It is very important to consider breast density in combination with this and other possible factors such as family history of breast cancer or identification of certain genes. The relationship between these factors is not completely understood and remains under investigation.
  • A woman with the highest breast density (BIRADS D) is estimated to have 2.2 times the average risk of interval cancer if she is 50-74, and 1.8 times risk if 40-49. An interval cancer is one diagnosed after a negative screen, and before the next regularly scheduled screen.
  • Program data demonstrate that dense breasts increase the risk of a “false positive” mammogram. This occurs when a screening mammogram is interpreted as positive when there is in fact no cancer present. It represents a downside to screening, but this downside also occurs for women with non-dense breasts.
  • The majority of women are at average risk of developing breast cancer. Screening mammography annually is not recommended for women who are otherwise at average risk. Women with a moderate risk (i.e., approximately 15 to 20 per cent lifetime risk of breast cancer), including most women who have a family history of breast cancer in a first-degree relative (mother, sister, daughter) are eligible for annual screening mammography.
  • Some scientific evidence exists that other tests, such as breast ultrasound, are able to detect additional cancers in women with dense breasts, but also have a high rate of false positives resulting in unnecessary biopsies.  Further evidence is necessary to understand the effect of supplemental screening on interval cancers and mammographic cancer detection beyond the first supplemental screening round. 
  • Current evidence suggests that most women with dense breasts and no additional risk factors for breast cancer not undergo supplemental screening with other imaging modalities given insufficient evidence demonstrating benefit1 2. Nevertheless, some women with dense breasts may reasonably opt to have supplemental screening, including those with a family history of breast cancer.
  • The J START RCT trial currently underway will provide further evidence to evaluate the harms and benefits of adding supplemental screening to select mammographically negative women.
  • The BC Medical Services Plan covers breast ultrasound when referred by a physician or nurse practitioner based on their clinical judgement, and in accordance with the provincial clinical guidelines. Women with new breast symptoms or breast changes should be investigated further, regardless of a recent negative mammogram.
  • The choice to have additional testing should be made on an individual basis after a discussion of the risks and benefits, along with the individual’s values and preferences with a health care provider.
1 Supplemental Screening for Breast Cancer in Women With Dense Breasts: A Systematic Review for the U.S. Preventive Services Task Force. Ann Intern Med. 2016;164(4):268. Epub 2016 Jan 12
As this is a complex issue, BC Cancer has formed a working group to implement a comprehensive set of new educational tools and support for patients and providers around breast density for province-wide roll out in the spring of 2019.

The Coldman Report on Breast Density is available here

A Q+A is available here

Screening for Women Who've Received Mantle Radiation for Hodgkin Lymphoma

Mantle field radiotherapy (or mantle radiation) treatment for Hodgkin lymphoma is a known risk factor for secondary breast cancer. The estimated actual incidence approaches 35% by 40 years of age. This increased risk begins about 10 years after treatment.

BC Cancer recommends that all women who received mantle radiation for Hodgkin lymphoma adhere to the following breast cancer screening routine:

  • Annual breast magnetic resonance imaging (MRI) starting at age 30 or 10 years after radiation treatment until the age of 65.
  • Annual screening mammogram starting at age 30 or 10 years after radiation treatment until the age of 74.
Letters have been sent to former Hodgkin’s lymphoma patients who have had mantle radiation, to invite them to participate in this higher level of screening so that any potential secondary breast cancer can be found early when it can be most successfully treated. For more information on these breast screening recommendations or to discuss your patient’s treatment history with a health care professional from BC Cancer, please call us at: 604-877-6292 or Toll Free 1-800-663-3333, ext 676292. 

For more information on breast cancer screening for women who received mantle radiation for Hodgkin lymphoma please see the Fact Sheet.

Talking to Patients

Women may hear conflicting information about screening. It’s important for them to be aware of the benefits and limitations of screening mammography so that they can make an informed decision. The Screening Mammography Decision Aid is available to support women in making an informed decision to screen for breast cancer using mammography.

Just the facts

  • The strongest risk factor for breast cancer is being female and getting older.
  • About 1 in every 8 Canadian women will develop breast cancer in her lifetime. 1 in 28 women is expected to die from the disease.
  • BC Cancer Breast Screening encourages eligible women to have a routine screening and sends reminder letters when women are due for their next screen.
  • The first mammogram is a baseline – returning regularly gives us the ability to compare images and find subtle changes that can occur over time.
  • Women can call 1-800-663-9203 directly to book an appointment.
  • BC Cancer Breast Screening has 36 fixed locations and 3 mobile services visiting over 120 communities across BC.

Benefits & Limitations

  • Mammograms save lives. Studies of screening programs around the world have demonstrated a 25% reduction in deaths from breast cancer among women who are screened.
  • Mammograms can usually find lumps earlier. Mammograms can show a breast lump 2 or 3 years before a woman or her primary care provider can feel it.
  • Detecting cancer at an early stage can make it easier to treat. Finding breast cancer early on may result in simpler treatment, more treatment options, and more positive outcomes.
  • Mammograms are not perfect. Factors like age and breast density may result in false-negative or false-positive mammograms.
  • Mammograms in younger women can be difficult to interpret. The dense breast tissue found in younger women can make it more difficult to find abnormalities.
  • Having a mammogram may lead to additional testing. Among women of all ages, about 7% of mammograms require diagnostic work up, which may include more imaging and/or biopsy.
  • Most abnormal findings detected on mammograms are not cancer. While 7% of women will need further testing after a screening mammogram, only 0.4% of screening mammograms in the BC Cancer Breast Screening program result in a diagnosis of breast cancer.
  • Screening mammography cannot detect all cancers. Mammograms find 4 in 5 cancers but some cancers that are detected by physical examination may not be seen on the mammogram. These cancers are often too small or in an area that is difficult to view, such as the axilla.
  • Mammograms expose women to low dose radiation. For most women, the benefits of regular mammograms outweigh the risks posed by this amount of radiation. 

Fast Track

Fast Track is a province-wide initiative aimed at reducing the time between an abnormal result and further testing. To speed up the process, BC Cancer Breast Screening sends results directly to the primary care provider (doctor, nurse practitioner or naturopathic doctor) and facilitates the referral for the first round of diagnostic testing. Once complete, the diagnostic results are sent to the primary care provider.

Contact with the Fast Track centre will occur as soon as possible. Patients typically receive their diagnostic tests faster than patients not participating in the Fast Track program. There may be some fluctuation in wait times for diagnostic follow up based on availability of appointments, workforce shortages, or patient availability but the goal is to complete any additional imaging in a timely manner. The Fast Track centre will contact the health care provider if unable to reach the patient directly.

  1. When your patient comes for a screening, she is told about the Fast Track system.
  2. You and/or your patient can choose a preferred clinic.
  3. If a preferred clinic is not selected, a default Fast Track clinic will be assigned. This is the closest Fast Track diagnostic imaging centre to the screening site; which is often the same location as the screening site.
  4. If further tests are needed (from an “abnormal”/recalled screen), BC Cancer Breast Screening faxes the Fast Track request with the BC Cancer Breast Screening report to the designated Fast Track centre. A copy is also faxed to the primary care provider office.
  5. BC Cancer Breast Screening sends the images and the radiologist’s recommendation for further imaging work up to the designated Fast Track centre.
  6. BC Cancer Breast Screening sends a result letter and the name of the Fast Track centre conducting further tests on your patient to the health care provider.
  7. The Fast Track centre contacts your patient to book the diagnostic imaging tests, usually within 1 week. The Fast Track centre will contact you (primary care provider) if the patient cannot be reached.
  8. You will receive a diagnostic imaging report from the Fast Track centre. The imaging work up will conclude with 1 of 3 outcomes:
    • All is clear, woman can return to regular screening
    • Probably benign: under these circumstances the woman is put on a “surveillance schedule” that may involve follow-up at 6 months, for 1 to 3 years
    • Recommend a biopsy, either percutaneous fine needle aspiration or core biopsy or open biopsy. If an open biopsy is recommended, you will be notified by phone or fax so that you can arrange referral for a surgical consultation.

SOURCE: Guidance ( )
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