Breast Screening Recommendations Summary

Screening people ages 40 to 49

The Ontario Breast Screening Program encourages women, Two-Spirit people, trans people and non-binary people ages 40 to 49 to make an informed decision about whether breast cancer screening is right for them. They can decide by talking to their primary care provider or a Health 811 navigator about:

• their personal risk for breast cancer
• the potential benefits and potential harms of breast cancer screening
• what matters most to them in taking care of their health

Prevention specialists, located in certain communities, can also help people make an informed decision about whether breast cancer screening is right for them.

Most women, Two-spirit people, trans people and nonbinary people ages 40 to 49 who decide to get screened for breast cancer should be screened with mammography every 2 years.

For advice on talking to patients, view Helping People Ages 40 to 49 Decide Whether to Screen for Breast Cancer. 

Screening people ages 50 to 74

The Ontario Breast Screening Program recommends mammography every 2 years for most women, Two-Spirit people, trans people and non-binary people ages 50 to 74.

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

Screening people who are pregnant or lactating

Screening with mammography during pregnancy or while lactating is safe and effective.

People who do not want to screen while pregnant can start screening three months after giving birth, even if they are lactating. Screening in the first three months postpartum is not recommended because there are changes in the breast tissue which can result in a mammogram being less effective.

Breast imaging for assessment or diagnosis should be managed as clinically appropriate throughout pregnancy and lactation.

Women, Two-Spirit people, trans people and nonbinary people ages 40 to 74 are eligible for screening through the Ontario Breast Screening Program 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 
• 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 people, trans people and nonbinary people to the Ontario Breast Screening Program or people can self-refer by contacting a screening location.

To find a location and its contact information, and to view mammogram appointment wait times, visit Ontario Health - Wait Times or call 1-866-662-9233.

Women, Two-Spirit people, trans people and nonbinary people over age 74 can be screened within the Ontario Breast Screening Program; however, we encourage them to make a personal decision about breast cancer screening in consultation with a primary care provider.

We will not recall people over age 74 to participate in the program. To continue screening through the Ontario Breast Screening Program, a referral is required from a primary care provider.

Potential benefits of regular breast cancer screening

Screening can find breast cancer early, which may mean that:

• treatment has a better chance of working
• treatment can be less intensive or invasive
• the chance of dying from breast cancer is lower

Potential harms of regular breast cancer screening

• A screening test result can sometimes be abnormal when someone does not actually have cancer (a false-positive). This may result in additional testing.
• Screening can find a cancer that would have never caused harm if left untreated (overdiagnosis). This could result in a surgery or treatment that was not needed.

Normal screening result

• The Ontario Breast Screening Program directly notifies participants (with or without a primary care provider) of their normal results by mail. The letter will also tell participants when to get screened again.
• The screening site also sends normal screening results to a screening participant’s primary care provider.

Abnormal screening result

• After a participant has an abnormal screening result, their screening site will notify their primary care provider and may help to schedule a timely follow-up appointment.
• A participant with an abnormal mammogram who does not have a primary care provider will be assigned to a primary care provider by their screening site to follow them to diagnosis. If the participant does have breast cancer, they will be referred to a specialist for further care and management.

The Ontario Breast Screening Program (OBSP) recommends that women, Two-Spirit people, trans people 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 people, trans people 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 people, trans people 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.

The High Risk Ontario Breast Screening Program (OBSP) site is responsible for communicating screening results to participants enrolled in the program.

Following an abnormal screening result, the High Risk OBSP site will notify the participant’s primary care provider and help to schedule a timely follow-up appointment.