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Breast Screening Guidelines Summary

This summary also available to download – Ontario Breast Screening Program (OBSP) Guidelines Summary.

Also see: Follow-Up of Abnormal Breast Screens

Screening Average Risk Women Ages 50 to 74 Years

Screening Recommendation

Mammogram every 2 years for most women.

Instances where a woman will be recalled by the program in 1 year:

  • Documented pathology of high-risk lesions
  • A personal history of ovarian cancer
  • 2 or more first-degree female relatives with breast cancer at any age
  • 1 first-degree female relative with breast cancer under age 50
  • 1 first-degree relative with ovarian cancer at any age
  • 1 male relative with breast cancer at any age
  • Breast density equal to or greater than 75% at the time of screening
  • Recommended by the radiologist at the time of screening

Ontario Breast Screening Program (OBSP) Eligibility

  • No acute breast symptoms
  • No personal history of breast cancer
  • No current breast implants
  • Has not had a screening mammogram within the last 11 months

How to Enrol a Patient

Healthcare providers can refer women to the Ontario Breast Screening Program (OBSP) or women can self-refer by contacting their local OBSP site.

For a list of locations and their contact information, view Breast Screening Centres or call 1-866-662-9233.

Outside the OBSP Screening Population

Women in their 40s are encouraged to make a personal decision about breast cancer screening in consultation with their healthcare provider.

Women over age 74 can be screened within the Ontario Breast Screening Program; however, they are encouraged to make a personal decision about breast cancer screening in consultation with their healthcare provider. The Ontario Breast Screening Program will not recall women over age 74 to participate in the program. To continue screening through the OBSP, a referral is required from a woman’s healthcare provider.

Why to Screen

  • Reduced risk of death from breast cancer with mammography screening for women ages 50 to 74
  • Breast cancer deaths in the Ontario population declined by roughly 42% for women ages 50 to 74 from 1990 to 2012. This is likely due both to improved breast cancer treatment and to increased participation in mammography screening.
  • Screening mammography has the ability to detect breast cancers when they are small, less likely to have metastasized to the lymph nodes and more likely to be treated successfully.

Screening high risk women ages 30 to 69 years

Screening Recommendation

Screening mammogram and screening breast magnetic resonance imaging (MRI) every year (or screening breast ultrasound if MRI is contraindicated) at High Risk OBSP sites.

High Risk OBSP Eligibility

  • Physician referral
  • Valid Ontario Health Insurance Plan (OHIP) number
  • No acute breast symptoms
  • Fall into one of the following risk categories:

Category A: Eligible for direct entry into the high risk breast screening program based on personal and family history.

Must meet one of the following risk criteria:

  • Known carrier of a gene mutation (e.g. BRCA1, BRCA2)
  • First degree relative of a carrier of a gene mutation (e.g. BRCA1, BRCA2), has previously had genetic counselling, and has declined genetic testing
  • Previously assessed by a genetic clinic (using the IBIS or BOADICEA tools) as having an equal to or greater than 25% personal lifetime risk of breast cancer based on family history
  • Received radiation therapy to the chest before age 30 and at least 8 years ago

Category B: Genetic assessment required to determine eligibility for high risk breast screening.

Must meet one of the following risk criteria:

  • First degree relative of a carrier of a gene mutation (e.g. BRCA1, BRCA2) and has not had genetic counselling or genetic testing
  • Personal or family history of breast or ovarian cancer.

How to Enrol a Patient

Refer women who might be at high risk for breast cancer to the OBSP by completing the OBSP Requisition for High Risk Screening and faxing it to a high risk screening site in your area. To find High Risk OBSP sites, view Breast Screening Locations.

The form serves as a referral for women who require genetic assessment to determine their program eligibility. It also authorizes the High Risk OBSP to book appropriate screening tests and follow-up of abnormal results.

Outside the Screening Population

High risk screening population: women ages 30 to 69

Women 70 to 74 years of age identified as high risk should be screened every year with mammography only at any Ontario Breast Screening Program site.

Women over age 74 can be screened within the Ontario Breast Screening Program; however, they are encouraged to make a personal decision about breast cancer screening in consultation with their healthcare provider. The Ontario Breast Screening Program will not recall women over age 74 to participate in the program. To continue screening through the OBSP, a referral is required from a woman’s healthcare provider.

Women at High Risk for Breast Cancer

  • The High Risk OBSP screens women ages 30 to 69 who are at high risk for breast cancer using a combination of mammography and magnetic resonance imaging (MRI) (or, if MRI is contraindicated, screening breast ultrasound).
  • Less than 1% of women in the general population are estimated to be at high risk.
  • Women at high risk have a greater estimated lifetime risk of developing breast cancer (up to 85%) than the general population (10 to 12%).
  • The sensitivity of mammography and MRI combined is greater than for mammography or MRI alone.

High Risk OBSP Referral Pathway

Limitations of Breast Cancer Screening

  • Mammography may miss some breast cancers and some cancers develop in the time between screens.
  • For every 200 women screened in the Ontario Breast Screening Program, about 17 are referred for further tests and 1 will have breast cancer.
  • Not all cancers found at screening can be treated successfully.
  • Some breast cancers that are diagnosed with screening may never cause symptoms in a woman during her lifetime (i.e., over-diagnosis). Therefore, some women may have surgery or treatment for a breast cancer that would not have become life-threatening.