Scientific Evidence Supports Breast Cancer Screening For Women in Their 40s

Nurse Assisting Patient Undergoing Mammogram

"Since 1-in-6 women who die from breast cancer are diagnosed in their 40s, we simply cannot afford to see missed opportunities for earlier detection" Palmaro said. "Scientific evidence, including data from British Columbia, shows that screening women in their 40s through organized programs can help to save lives."

Strong scientific evidence and public demand exists for screening Canadian women aged 40-49 for breast cancer, the Canadian Breast Cancer Foundation (CBCF) said today in response to new screening guidelines released by the Canadian Task Force on Preventive Health Care.

“The fact is scientific evidence demonstrates that earlier detection and diagnosis can save lives among women 40-49 by at least 25%,” said Sandra Palmaro, CEO, Canadian Breast Cancer Foundation – Ontario Region.

Palmaro added that screening can help find cancers that are smaller and haven’t spread, which can allow for better treatment options and reduced disability and death from breast cancer. Breast cancer continues to be the most frequently diagnosed cancer among Canadian women.

One of CBCF’s most significant concerns about the Task Force report is that it relied heavily on old data from “randomized controlled trials” (RCT’s) related to breast cancer screening and mammography, some of which are 25 – 40 years old and were based on equipment that is now outdated. There has been an enormous change in breast imaging since that time, including significant improvements to analog technology, and the continued adoption of digital mammography across Canada. Digital mammography has been shown to increase accuracy in younger women pre and perimenopausal women, and women with dense breasts, the group the Task Force recommends be excluded.

“This undermines the scientific basis for the Task Force’s conclusions,” said Dr. Martin Yaffe of Sunnybrook Research Institute. “Screening technology is significantly more sophisticated and accurate at detecting breast cancer today than it was when those studies were done.”

Dr. Yaffe chaired a Scientific Advisory Committee during the CBCF It’s About Time conference that included in its review more recent observational studies from Europe and Canada. The conference’s It’s About Time report issued in October, 2010, concluded that there are benefits of screening women in their 40’s that include savings lives through earlier diagnosis.

“All RCTs have limitations due to non-compliance (when women invited to be screened decline) and contamination (when women in the control group have mammography outside the trial) and therefore RCTs also underestimate the benefits of screening,” says Dr. Paula Gordon of BC Women’s Hospital.

“It’s critically important to consider these issues in the context of today’s technology and in terms of the real life experiences of Canadian women. That evidence strongly supports screening women beginning at age 40,” said Gordon. “Our own data from BC show 25-39% mortality reduction among screened women aged 40-49. And these data were derived even before widespread implementation of digital mammography.”

CBCF is encouraging the six provinces and territories where women 40-49 are not eligible to participate in their organized screening program – Ontario, Manitoba, Newfoundland and Labrador, New Brunswick, Quebec and Saskatchewan – to take a first step in allowing women 40-49 access to organized screening programs where possible and if recommended by a health care provider. This is the current practice in Alberta while in BC, Nova Scotia, PEI, Northwest Territories and Yukon women do not require a health care provider’s recommendation to participate in organized screening programs.

CBCF’s position is also consistent with the breast cancer screening guidelines from the National Cancer Institute, the American Cancer Society, and the American College of Obstetricians and Gynecologists, all of which recommend that women begin screening at 40 years of age.

“Since 1-in-6 women who die from breast cancer are diagnosed in their 40s, we simply cannot afford to see missed opportunities for earlier detection” Palmaro said. “Scientific evidence, including data from British Columbia, shows that screening women in their 40s through organized programs can help to save lives.”

While all screening tests, including mammography, have both benefits and limitations, Canadian women appear to be more concerned about being thoroughly-tested than the possibility of a false alarm. A recent Canadian survey conducted by Strategic Communications Inc, sought the views of 1,670 women on the topic of breast cancer screening.

When surveyed, women were provided information about the potential for “false positives” during screening and what the outcomes of those results could be, 87.5 per cent of respondents still felt organized screening for women 40-49 offered either “much more benefit” or “more benefit” than limitation.

The survey found that if offered the choice between two theoretical screening tests:

A majority (63 percent) of Canadian women would choose a screening test that “never misses cancer but 1-in-10 tests are false alarms.” Only 20 per cent would choose a test that “misses 1-in-3 cancers but gives no false alarms.” CBCF encourages women to make an informed decision about breast cancer screening by learning about the benefits and limitations of screening and to speak with a health care provider about what is right for them.

“While recognizing governments’ need to make prudent budget decisions and the need for women over age 50 to continue to have full access to organized screening, CBCF believes we should work toward all Canadian women aged 40-49 participating in provincial and territorial organized breast cancer screening programs with a healthcare provider’s recommendation,” Palmaro said.