Breast Screening Guidelines Summary

The Ontario Breast Screening Program recommends mammography every 2 years for most women, Two-Spirit, trans and nonbinary people.

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

• Documented pathology of high-risk lesions
• A personal history of ovarian cancer
• Two or more first-degree relatives assigned female at birth with breast cancer at any age
• One first-degree relative assigned female at birth with breast cancer under age 50
• One first-degree relative with ovarian cancer at any age
• One breast cancer at any age in a relative assigned male at birth
• Breast Imaging Reporting and Data System (BI-RADS) breast density category D
• Recommendation by the radiologist at the time of screening or assessment

Women, Two-Spirit, trans and nonbinary people ages 50 to 74 are eligible for screening through the OBSP if they:

• Have no breast cancer symptoms
• Have no personal history of breast cancer
• Have not had a mastectomy
• Have not had a screening mammogram within the last 11 months, and
• If transfeminine (i.e., assigned male at birth), have used feminizing hormones for at least 5 consecutive years.

Primary care providers can refer women, Two-Spirit, trans and nonbinary people to the Ontario Breast Screening Program (OBSP) or people can self-refer by contacting their local OBSP site.

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

People ages 40 to 49 who are at average risk for breast cancer are encouraged to make a personal decision about breast cancer screening in consultation with a family doctor or nurse practitioner. The primary care provider can provide a referral for a mammogram if the someone would like to be screened.

Women, Two-Spirit, trans and nonbinary people over age 74 can be screened within the OBSP; however, they are encouraged to make a personal decision about breast cancer screening in consultation with a primary care provider. The OBSP will not recall people over age 74 to participate in the program. To continue screening through the OBSP, a referral is required from a primary care provider.

• There is a reduced risk of death from breast cancer with mammography screening for people ages 50 to 74
• Screening mammography can detect breast cancers when they are small, less likely to have metastasized to the lymph nodes and more likely to be treated successfully.

The Ontario Breast Screening Program (OBSP) recommends that women, Two-Spirit, trans and nonbinary people ages 30 to 69 who meet the High Risk OBSP eligibility criteria get screened once a year with mammography and breast magnetic resonance imaging (MRI) (or screening breast ultrasound if breast MRI is not medically appropriate) every year.

Women, Two-Spirit, trans and nonbinary people ages 30 to 69 can get screened through the High Risk OBSP if they have a referral from their primary care provider, a valid Ontario Health Insurance Plan number, no breast cancer symptoms and meet criteria listed in Category A or B (see below).

Category A – Eligible for direct entry into the High Risk OBSP based on personal and family history. To fall under this category, at least one of the following criteria must be met:

• Known carrier of a pathogenic or likely pathogenic gene variant (e.g., BRCA1, BRCA2, TP53, PALB2) that increases their risk for breast cancer
• Have not had genetic testing, but have had genetic counselling because they are a first degree relative of a carrier of a pathogenic or likely pathogenic gene variant (e.g., BRCA1, BRCA2, TP53, PALB2) that increases their risk for breast cancer
• Previously assessed by a genetics clinic (using the IBIS or CanRisk risk assessment tools) as having a 25% or greater lifetime risk for breast cancer based on personal and family history
• Have had radiation therapy to the chest to treat another cancer (e.g., Hodgkin Lymphoma) before age 30 and at least eight years ago

Category B – Genetic assessment required (i.e., counselling and/or testing) to determine eligibility for the High Risk OBSP. To fall under this category, at least one of the following criteria must be met:

• An identified pathogenic or likely pathogenic gene variant that is associated with breast cancer risk (e.g., BRCA1, BRCA2, TP53, PALB2) in a close blood relative
• A personal or family history of a cancer suggestive of a hereditary breast cancer syndrome.

People with a personal history of breast cancer and/or breast implants may get screened through the High Risk OBSP if they meet program eligibility criteria.

The High Risk OBSP does not accept new participants over age 70. However, when participants already in the High Risk OBSP turn 70, the program will continue to screen them with mammography only every year until they are age 74.

High Risk OBSP sites do not send letters to people over age 74 about participating in the program. To continue screening through the High Risk OBSP, a referral is required from a primary care provider.

Refer eligible people to the High Risk Ontario Breast Screening Program (OBSP) by completing the High Risk OBSP Requisition Form and faxing it to a High Risk OBSP site in your area. To find a site, please visit High Risk OBSP Locations.

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

High Risk Ontario Breast Screening Program (OBSP) screening population: women, Two-Spirit, trans and nonbinary people ages 30 to 69.

The High Risk OBSP does not accept new participants over age 70. However, when participants already in the High Risk OBSP turn 70, the program will continue to screen them with mammography only every year until they are age 74.

High Risk OBSP sites do not send letters to people over age 74 about participating in the program. To continue screening through the High Risk OBSP, a referral is required from a primary care provider.