Cancer COVID-19 (coronavirus) Featured

Undetected breast cancers are a serious side effect of the COVID-19 pandemic

image of mammogram
Written by Sunnybrook

When the COVID-19 pandemic was declared in March 2020, cancer screening programs were paused in Ontario. No one knew what COVID-19 would bring and that looming health-care crisis was understandably prioritized.

But now, nearly a year later, there’s another crisis brewing beneath the surface: undetected breast cancers.

In a regular year, about 73,000 women participate in the Ontario Breast Screening Program (OBSP), which invites women aged 50-74 for a screening mammogram every two years. Each year, about 430 of those women go on to receive a diagnosis of breast cancer.

Last year, just 28,000 Ontario women underwent screening mammography. Those tests detected 148 cancers, most at their early stages. The missing mammograms mean about 200 more women in Ontario have undetected breast cancers.

Is it time for your mammogram? Don't delay. Book your appointment

Screening mammography is a test done on people who are at risk of getting cancer, but have no symptoms of the disease. The goal of a screening test is to detect breast cancer in its earliest stage, when it’s more curable and requires less aggressive treatment. Research shows that early detection helps reduce breast cancer deaths.

The decline in screening tests means instead of catching a cancer when it is small and undetectable by a physical exam, a woman seeks medical care when she notices a lump or change in her breast. By then, it’s more likely the cancer will be advanced. And while we can’t turn back time to know if an advanced cancer might have been seen on a screening test, we do know that a screening test is one step we can take to try to catch breast cancer early.

At Sunnybrook, our OBSP screening site reopened last summer when we were permitted to do so, and since, the team has been holding some “Saturday Blitzes” to get through the backlog of breast screening tests. Our backlog is cleared, and if you are due for a mammogram, we want to see you.

If you missed a mammogram in 2020 or are due for one in 2021, please call your health-care provider or screening site and book it today.

We have heard from women that they were frightened to come to the hospital. We have also heard that some didn’t think their screening would take place because it isn’t important. It is important and we want to reassure you, it is safe. We have COVID-19 safety rules in place to protect you and our staff.

And, if something highly suspicious is spotted on your test, your health-care professional can refer you to the Marion Solway Breast Rapid Diagnostic Unit, where investigation with a diagnostic mammogram, ultrasound and biopsy are performed and a rapid diagnosis provided within 24-48 hours of those tests.

It’s particularly important for high-risk women to undergo routine screening. If you have a family history of breast and/or ovarian cancer, you can be referred to the High-Risk Breast Clinic at Sunnybrook’s Louise Temerty Breast Cancer Centre where our team of physicians, radiologists who specialize in breast imaging and genetic counsellors can assess if you are at high-risk of developing breast cancer and if so, provide you with recommendations for screening and risk-reducing strategies.

As always, if you notice a lump or change in your breast, please contact your health-care provider right away.

As 2021 gets underway with COVID-19 still a part of it, we all must balance the risks of COVID-19 against the harms related to interruptions in cancer screening, including the development of more cases of advanced cancer requiring more aggressive treatments, utilization of health care resources and cancer-related deaths. Please ask your health-care provider about cervical, lung and colorectal cancer screening as well. If you do not have a family doctor or nurse practitioner, contact Health Care Connect by calling 1-800-445-1822 or visit to be connected to a primary care provider.

What are you doing next Saturday? We hope you’ll consider booking your mammogram screening test. It could save your life.

If you have breast tissue, it is recommended that you be screened according to provincial guidelines, regardless of your gender identity or sexual identity. Ontario Health (Cancer Care Ontario) is working to implement a policy for the inclusion of trans and gender diverse people in its organized screening programs. More info can be found here.

Blog authors:

Dr. Eileen Rakovitch
Medical Director
Louise Temerty Breast Centre
Sunnybrook Health Sciences Centre
Dr. Andrea Eisen
Medical Oncologist and Lead, High-Risk Program
Louise Temerty Breast Centre
Sunnybrook Health Sciences Centre
Co-chair, CCO Breast Site Group

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