New breast cancer screening guidelines are outdated and dangerous, experts say

A letter from 130 experts on breast cancer says new screening guidelines proposed by the Canadian Task Force on Preventive Health Care are outdated and “dangerous.”

The new guidelines were released in December and are meant to help guide medical practitioners. They state women between the ages of 40-49 do not need mammograms, and older age groups only need to be given a mammogram every two or three years.

WATCH: Questions are being raised about whether new breast cancer screening guidelines – recommending that women under the age of 49 not be screened — are putting women at risk. As Heather Yourex-West explains, one cancer survivor diagnosed at 35 is asking why more women like her aren’t being offered routine screens.

1:59 Concerns raised over new breast cancer screening guidelines

(The recommendations are for the general public, and exclude women who are more at risk of getting breast cancer because of genetic mutations or family history.)

“It is erroneous and dangerous to recommend against screening women 40-49,” the letter reads, saying all women over 40 should be screened annually.

WATCH: Expert panel says patients should decide when to get mammograms

1:52 Expert panel says patients should decide when to get mammograms

The guidelines also say they don’t recommend physical breast exams, either done by the woman herself or her doctor, because “there was evidence that performing breast self-examination has no impact on breast cancer mortality.”

But more than 130 breast-cancer doctors and researchers disagree – saying the task force is basing their recommendations on data collected before the year 2000.

“They’re based on studies that are as old as 60 years, that was started in the 1960s,” said Martin Yaffe, researcher at Sunnybrook Health Sciences Centre in Toronto. “Those studies were conducted using screening methods that we don’t use anymore.”

“The benefit (of reducing mortality by screening) was really underestimated because things have improved so much since that time,” he said.

Tweet This Click to share quote on Twitter: "The benefit (of reducing mortality by screening) was really underestimated because things have improved so much since that time," he said.

Statistics quoted by Dense Breasts Canada say women who have mammograms are 40-60 per cent less likely to die of breast cancer than women who don’t have mammograms. But it says the task force only estimated this number to be 15 per cent.

WATCH: Ask the Doctor: Detecting breast cancer

3:47 Ask the Doctor: Detecting breast cancer

But task force member and University of Alberta professor Scott Klarenbach said the data they used was “high quality” data based on randomized control trials.

“We kind of use a systematic approach to make sure we get all the information available,” he said.

Tweet This Click to share quote on Twitter: "We kind of use a systematic approach to make sure we get all the information available," he said.

He agreed that there is a lack of more recent “high quality” data – but said the guidelines are in line with other country’s guidelines – like the U.S. and the U.K.

Another issue the letter expresses with the task force’s recommendations is that the guidelines aren’t written by breast-cancer doctors. Instead, they’re written by doctors with other expertise.

WATCH: B.C. to begin breast density screening

2:06 B.C. to begin breast density screening

Klarenbach, whose specialty is nephrology (the study of the kidneys) says this is purposely done to prevent bias or the appearance of bias in the recommendations.

The task force says they need to weigh the benefits versus harms of screening.

Some of the harms referenced in the task force’s report include overdiagnosis, which means finding a cancer that wouldn’t have caused harm to the patient, and an increase of anxiety for the patient while waiting for conclusive test results.

WATCH: Author Renée Pellerin talks harm vs benefits of mammograms

3:39 The truth about breast cancer screening

But the letter alleges, “The Task Force has overstated the incidence of overdiagnosis.” It states overdiagnosis occurs in less than 10 per cent of cases and the benefit of finding harmful cancer outweighs the risk of finding a cancer that might not kill the patient, (if she dies of another cause).

The recommendations don’t mention breast density, a topic that’s been more talked about in recent years.

“The Task Force has ignored the issue of breast density… And they have failed to acknowledge that supplementary screening for women with dense breasts can find the cancers missed on mammograms in these women,” the letter from experts read.

Since research has shown that mammograms are less likely to find cancer in a breast with high density, Yaffe and other doctors recommend using MRIs or ultrasounds to screen women with dense breasts.

He also says women with dense breast should “examine her own breasts on a regular basis and just look for changes” – but the task force says it doesn’t recommend administering self-exams.

Klarenbach stressed that these guidelines are for women who don’t have any symptoms, and that all women should have a conversation with their doctor about screening.

“This is a screening program or prevention program. It’s a little bit different than women coming to see their doctor for a symptom or a problem,” he said.

Tweet This Click to share quote on Twitter: "This is a screening program or prevention program. It's a little bit different than women coming to see their doctor for a symptom or a problem," he said.

Dense Breasts Canada has started a petition to ask Canada’s health minister to reject the guidelines.

While Health Canada does link to the task force’s information, a spokesperson from the department told Global News that does not amount to an endorsement, saying their goal is to inform Canadians.

The petition has more than 3,000 signatures as of the time of publication.