Thank you.

Honourable health committee members, the Canadian task force understates the benefits of screening, but they are obsessed with what they call the harms. They recommend against screening women in their forties, even though women aged 40 to 49 are 44% less likely to die of breast cancer if they have mammograms. They recommend against supplemental screening for women with dense breasts, even though many more invasive cancers would be found earlier if it were used.

I'll explain what they think the harms are. Even that term is misleading. They really are the risks or limitations.

The first is the anxiety women experience if they are recalled for additional tests after a screening mammogram and are not found to have cancer. Only about 5% of recalled women are diagnosed with cancer. That anxiety is real, but it's transient, and it pales in comparison to the anxiety a woman feels if she learns that she has an advanced cancer and that she faces the possibility of death or at least months of surgery, radiation and chemotherapy, which might have been avoided had her cancer been found earlier.

The task force gives false equivalence of this anxiety to delayed diagnosis and advanced cancer. The task force also disproportionately focuses on overdiagnosis. You just heard that this is the theoretical possibility in which a woman is diagnosed with cancer and is treated for it but dies of another cause sooner than her breast cancer would have killed her. For example, she may die of a heart attack sooner.

Overdiagnosis is much less common in younger women. They're less likely to die of other causes, and their cancers are more aggressive than are those in older women, so they grow and spread faster if untreated. In women in their forties who get breast cancer, breast cancer accounts for 91% of their deaths, but in women in their seventies, it accounts for only 48%.

Cancers do not regress if they're left untreated. They may grow quickly or slowly, but given time they will spread and kill. Doctors Wilkinson and Seely, working with Stats Canada, showed that after screening of women in their forties was stopped in response to the task force recommendations in 2011, the rate of metastatic cancer went up by 10% for both women in their forties and those in their fifties.

Overdiagnosis is only important if it leads to overtreatment. With current testing and rapidly advancing research on predicting how a given cancer will behave, oncologists can offer less aggressive treatment for some cancers, but if women choose not to be screened because of the task force's emphasis on overdiagnosis, they lose the opportunity to find their cancers early and save lives.

In their 2018 review, the task force said that the rate of overdiagnosis was 48%, based mainly on an old, flawed Canadian study that has been discredited. For the current review, overdiagnosis was 11% when that discredited study was included but only 6% when it was excluded. That 48% rate included in the decision tool created by the task force and used in shared decision-making may well have been responsible for countless deaths.

Screening is not perfect. Women should be told about the risks of being recalled and overdiagnosis, but they should not be discouraged from screening. Some members of the task force say that screening is less important because treatment is getting better, but it's not a contest. Screening and treatment are synergistic. Cancer can be treated more effectively and less aggressively when it's found earlier.

Of course, there are anecdotal studies of women with early cancer who didn't do well and women with stage three who did do well. However, it's like hearing stories about people who smoked all their lives and died at age 95 without developing lung cancer. Reliable data trumps outlier stories.

Some members of the task force claim that screening can't save the lives of women with rapidly growing cancers. That's not true. Stats Canada has shown that when triple negative cancer is detected at stage one, the five-year survival is 96%, but at stage four, it's only 7%. The stage of diagnosis does matter, and it's about more than just saving lives. Chemotherapy can often be avoided when cancer is found early. Most patients with stage one cancer don't need chemo. Most patients with stage two and higher do need it. The stage of diagnosis does matter.

Early detection also allows for less aggressive surgery—lumpectomy instead of mastectomy, sentinel lymph node biopsy versus axillary dissection. The traditional armpit surgery to sample lymph nodes leads to permanent swelling of the hand and arm in about one-third of women. The stage of diagnosis does matter.

To sum up, the science is clear: Screening finds cancer at a lower stage, improves the quality of life for women with cancer and saves more lives. The alleged harms are not reason enough to deny or discourage women from the opportunity for early detection. If screening is not offered starting at age 40, it will be inaccessible for many women. No one is going to force a woman to have screening, but she needs to have the choice whether to attend.

Thank you very much.