Helping People Ages 40 to 49 Decide Whether to Screen for Breast Cancer

What’s on This Page

• Why Breast Cancer Screening Conversations Are Important
• Eligibility for People Ages 40 to 49
• Setting the Stage for Decision-Making
• Risk of Breast Cancer
• Race, Ethnicity and Indigeneity
• Values and Preferences for Breast Cancer Screening
• Next Steps After Deciding Whether to Screen
• Jurisdictional Evidence on Race, Ethnicity and Indigeneity
• References

Why Breast Cancer Screening Conversations Are Important

The Ontario Breast Screening Program (OBSP) encourages people ages 40 to 49 to make an informed decision about whether breast cancer screening is right for them based on:

• 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

Having conversations about breast cancer screening is important because:

• generally people ages 40 to 49 have a lower chance of getting breast cancer compared with people ages 50 to 74
• the balance of potential benefits to potential harms of regular breast cancer screening may be different for people ages 40 to 49 than for people ages 50 to 74

Eligibility for the Ontario Breast Screening Program

Women, Two-Spirit people, trans people and nonbinary people ages 40 to 49 are eligible for breast cancer screening in 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, have used feminizing hormones for at least 5 years in a row

There is also a program for people who are at high risk of getting breast cancer based on:

• whether they have certain genes
• their family or personal health history
• whether they have previously had radiation therapy to the chest

To learn more about the high risk screening program, go to Ontario Breast Screening Program or call the Ontario Health Contact Centre at 1-866-662-9233.

Setting the Stage for Decision-Making

Make sure the person you are counselling understands that their choice is between getting screened now or not getting screened right now. Reassure them that:

• they can take as much time as they need to decide
• if they choose not to screen, they can change their mind and start screening at any time between age 40 to 74

Note: Eligible people will receive an invitation letter to start screening when they turn 50.

Risk of Breast Cancer

Breast cancer is the most commonly diagnosed cancer in Ontario, but most breast cancers are found in people ages 50 and over.

Source: Statistics Canada. Table 13-10-0111-01 Number and rates of new cases of primary cancer, by cancer type, age group and sex.

*The binary-only sex statistics reported in this section reflect how the data are recorded in the data source and are not inclusive of all gender diversity. As a result, the data may incorrectly classify people whose gender identity differs from their sex assigned at birth.

Each person’s chance of getting breast cancer differs based on their individual risk factors. People can use My CancerIQ to understand how their risk of breast cancer compares to others in their age group and get personalized information on how they can decrease their risk of breast cancer. Understanding their own risk may help them make a decision about breast cancer screening.

Race, Ethnicity and Indigeneity

Note: The binary-only sex statistics reported in this section reflect how the data are recorded in the data source and are not inclusive of all gender diversity. As a result, the data may incorrectly classify people whose gender identity differs from their sex assigned at birth.

• Data show differences specific to race, ethnicity and Indigeneity in breast cancer subtype, stage at diagnosis, incidence, mortality and survival.
• It is currently unknown how screening people in Ontario ages 40 to 49 may impact outcomes across different racial and ethnic groups and for First Nations, Inuit, Métis and urban Indigenous people. Although there is not enough evidence to provide specific breast cancer screening recommendations based on race, ethnicity and Indigeneity, it is important for providers to help their patients understand the available evidence so they can make an informed decision based on their individual risk.
• Be cautious about applying the data from other jurisdictions to the Ontario context.
• This high-level summary includes available evidence from Canada, the United States and the United Kingdom:
  • Age at breast cancer diagnosis for non-white female populations has been found to be younger than in white females in certain studies from Canada and the United Kingdom. [1, 2]
  • Canadian and United Kingdom studies showed that Black females have more aggressive tumour profiles compared with white females. [1,3]
  • Canadian, United States and United Kingdom studies showed that the incidence of breast cancer is lower in some racial and ethnic groups than in white females. [1,4,5,6]
  • Black females have a higher breast cancer mortality rate than white females in Canada and the United States. [1,7]
  • First Nations females in Ontario have lower breast cancer incidence and mortality rates than other females in Ontario, but they also have a lower survival rate. [8] (Note: “Other females” include females living in Ontario, except First Nations in the Indian Register and Métis in the Métis Citizenship Registry.)
  • Breast cancer incidence was significantly higher for Métis women than for non-Indigenous women in Canada. [9]
  • Breast cancer incidence was lower among female residents of Inuit Nunangat compared to female residents in the rest of Canada. [10]
• People of Ashkenazi Jewish descent have a higher risk of developing breast cancer because genetic variants in the BRCA1 and BRCA2 gene are more common in this population. If your patient is of Ashkenazi Jewish descent, age 30 to 69 and has a personal or family history of breast or ovarian cancer, they may be eligible for screening in the High Risk OBSP. To find out more about the High Risk OBSP and access the program requisition form, visit Breast Cancer Screening for People at High Risk.
• Also consider that disparities specific to race, ethnicity and Indigeneity reflect determinants outside of biological differences. These include, but are not limited to:
  • individual barriers (limited awareness, fear or distrust)
  • community or interpersonal barriers
  • structural barriers
  • social or historical factors
  • structural racism
  • inequities in the healthcare system

For more detailed information on breast cancer incidence and outcomes specific to race, ethnicity and Indigeneity, see Jurisdictional Evidence.

Values and Preferences for Breast Cancer Screening

As you review the potential benefits and potential harms with people ages 40 to 49, ask them which are most important to them, and what matters most to them about breast cancer screening.

Potential benefits and potential harms of screening exist regardless of the age at which someone decides to screen; however, the balance of potential benefits to potential harms may change based on someone’s age.

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.

Source: Trentham-Dietz A, Chapman CH, Jayasekera J, et al. Collaborative Modeling to Compare Different Breast Cancer Screening Strategies: A Decision Analysis for the US Preventive Services Task Force. JAMA. Published online April 30, 2024. doi:10.1001/jama.2023.24766 https://jamanetwork.com/journals/jama/fullarticle/2818285

*The binary-only sex statistics reported in this section reflect how the data are recorded in the data source and are not inclusive of all gender diversity. As a result, the data may incorrectly classify people whose gender identity differs from their sex assigned at birth.

The data in this section are derived from 5 simulation models of breast cancer in United States female populations screened using digital 2D mammography. Data includes all screens (initial screens and rescreens). There are limitations to modelling: assumes 100% participation, all abnormal screens receive prompt evaluation and immediate treatment. These numbers will be updated to reflect Canadian data when the final Canadian Task Force on Preventive Health Care modelling is updated and released.

Advising people who are pregnant or lactating

• Counsel them about their screening options:
  • People who are pregnant can be screened safely with mammography.
  • People who do not want to screen while pregnant can start screening 3 months post-partum, even if they are lactating.
• Counsel them about the signs and symptoms of pregnancy-associated breast cancer.

Next Steps After Deciding Whether to Screen