Screening for Breast Cancer

Cancer screening is testing done on people who may be at risk of getting cancer, but who have no symptoms and generally feel fine. Screening can find breast cancers when they are small, less likely to have spread and more likely to be treated successfully. Women ages 50 to 74 have a lower risk of dying from breast cancer when they are screened regularly with mammograms.

Mammography is the process of using low-energy x-rays (usually around 30 kVp) to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer typically through detection of characteristic masses or microcalcifications.

Like all X-rays, mammograms use doses of ionizing radiation to create images. These images are then analyzed for any abnormal findings. It is normal to use lower-energy X-rays, typically Mo (K-shell x-ray energies of 17.5 and 19.6 keV) and Rh (20.2 and 22.7 keV) than those used for radiography of bones.  Ultrasound, ductography, positron emission mammography (PEM), and magnetic resonance imaging (MRI) are adjuncts to mammography. Ultrasound is typically used for further evaluation of masses found on mammography or palpable masses not seen on mammograms. Ductograms are still used in some institutions for evaluation of bloody nipple discharge when the mammogram is non-diagnostic. MRI can be useful for further evaluation of questionable findings as well as for screening pre-surgical evaluation in patients with known breast cancer to detect any additional lesions that might change the surgical approach, for instance from breast-conserving lumpectomy to mastectomy. Other procedures being investigated include tomosynthesis.

Ontario Breast Screening Program (OBSP)

The Ontario Breast Screening Program (OBSP) is a province-wide, organized cancer screening program. It provides high-quality breast cancer screening throughout Ontario to 2 groups of women, and recommends that most women ages 50 to 74 get screened every 2 years with mammography,  women ages 30 to 69 who are confirmed to be at high risk of developing breast cancer get screened once a year with a mammogram and breast magnetic resonance imaging (MRI) (screening breast ultrasound if MRI is not medically appropriate). Women ages 30 to 69 can get screened through the High Risk OBSP if they have a referral from their doctor, valid OHIP coverage no acute breast symptoms, and fall into one of the following risk categories:

  • Are known to have a gene mutation that increases their risk for breast cancer (e.g., BRCA1, BRCA2, TP53, PTEN, CDH1)
  • Are first-degree relatives (parent, brother, sister or child) of someone who has a gene mutation that increases their risk for breast cancer (e.g., BRCA1, BRCA2, TP53, PTEN, CDH1), have already had genetic counselling and have chosen not to have genetic testing
  • Have been assessed at a genetics clinic (using the IBIS or BOADICEA tools) as having a 25 percent or greater lifetime risk of breast cancer based on personal and family history
  • Have had radiation therapy to the chest to treat another cancer or condition (e.g., Hodgkin lymphoma) before age 30 and at least 8 years ago

Women should talk with their doctors about regular breast cancer screening. Studies show that regular mammograms lower the risk of dying from breast cancer in women ages 50 to 74.

Program Benefits

Screening mammography can find breast cancers when they are small, less likely to have spread and more likely to be treated successfully. Women ages 50 to 74 are encouraged to get screened through the Ontario Breast Screening Program (OBSP) to receive all the program benefits.

Communication to Women and Healthcare Providers

  • Women eligible for screening through the OBSP are sent invitations to get screened, along with information about breast cancer screening and details on how to find an OBSP site.
  • After their screening appointment, women with normal screening results get letters telling them their results are normal..
  • Women screened in the OBSP get letters reminding them when to get screened again.
  • OBSP sites send normal and abnormal screening results to a woman’s healthcare provider and follow-up on abnormal screening results.

Coordination and Navigation

  • High Risk OBSP sites connect women referred to the program with genetics clinics for genetic assessment, if appropriate.
  • High Risk OBSP sites book appointments for screening mammography and screening breast magnetic resonance imaging (MRI) (or screening breast ultrasound if MRI is not medically appropriate).
  • The OBSP indicates whether a woman should be screened in 1 year or 2 years based on her screening results and risk factors.
  • OBSP assessment sites help guide women with abnormal screening results through to diagnosis by coordinating follow-up tests and documenting the results of those tests.

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