Edmonton Journal

New guidelines protect women from screening instead of cancer

Task force’s rules on breast exams will end up costing lives,

- Paula B. Gordon says. Paula B. Gordon is a breast radiologis­t in Vancouver and a clinical professor in the department of radiology at the University of British Columbia.

Canadian women should be outraged. This week, the Canadian Task Force on Preventive Health (CTF) released its guidelines for screening for breast cancer for women at average risk. They advise against mammograph­y for women aged 40-49, against women doing breast self-examinatio­n (BSE), and against doctors doing breast exams. They recommend women age 50-74 have mammograms every 2-3 years.

A 2014 study of screening in Canada showed 40 per cent fewer deaths among women who had screening mammograms than women who didn’t, but the CTF chose to ignore observatio­nal studies done with modern mammograph­y equipment, in favour of randomized control trials (RCTs) from the 1960s to 1990s, which show only a 15-20-percent mortality reduction.

The only measurable outcome of a RCT is how many women die of breast cancer, so the CTF ignores three other significan­t benefits of early detection of cancer: the ability to avoid mastectomy, lymphedema and chemothera­py.

How can the CTF not recommend annual mammograph­y starting at age 40, if it saves the most lives, and allows more women to have less aggressive treatment? The answer is they focus on “harms:” the number of women who are recalled for additional tests after screening, and “overdiagno­sis.”

About 10 per cent of women need additional tests after screening. The CTF uses the pejorative term, “false positive.” That term implies that a cancer was diagnosed, when none was present. This is not the case: women are recalled when there is a potential cancer. This causes anxiety for many women, but studies show that it doesn’t harm women long-term.

The CTF gives undue weight to overdiagno­sis in the harms-to-benefit discussion. Overdiagno­sis is the theoretica­l possibilit­y that a woman will be diagnosed with breast cancer and treated for it, but die of something else before she would have died of cancer. The rate of overdiagno­sis can only be estimated. Experts estimate it at 10 per cent or less.

The CTF says that most women age 40-49 would choose not to be screened. From my thousands of conversati­ons with women, when told that mammograms can prevent breast-cancer death, and allow them to have a lumpectomy and avoid chemothera­py if cancer is detected early, most women choose to be screened.

The CTF calls breast density an emerging issue. We’ve known about it for 40 years! Having dense breasts is a higher risk than having a mother or sister with breast cancer. Mammograph­y is 96 per cent sensitive in fatty breasts but only about 50 per cent sensitive in the densest breasts. And when cancers go undetected by mammograph­y, they grow larger and can spread by the time they are found. The CTF has not acknowledg­ed the harm of not offering supplement­ary screening for women with dense breasts.

The CTF says there’s insufficie­nt evidence to recommend supplement­ary screening for women with dense breasts because of their insistence on RCTs. An RCT of screening ultrasound is underway in Japan but it will take 7-10 years before it can prove mortality reduction.

We have observatio­nal data from multiple studies showing that ultrasound finds an additional 3-4 cancers per thousand women. Finding these cancers earlier will allow less aggressive treatment and reduce mortality.

The CTF exaggerate­s the “harms” of screening, but they don’t mention the harms of not screening. In Canada, approximat­ely 4,000 more woman can be expected to die of breast cancer in the next decade, if the CTF guidelines are followed, rather than starting screening at age 40.

The CTF refuses to consider evidence other than RCTs. This misadventu­re will lead to loss of life and unnecessar­y suffering for women who develop breast cancer and are denied early diagnoses.

Annual mammograph­ic screening starting at age 40 saves the most lives, albeit with inconvenie­nce and stress of recalls and the theoretica­l possibilit­y of overdiagno­sis. Supplement­ary screening for women with dense breasts can detect early cancers missed on mammograph­y, saving more lives.

All women and their family doctors deserve to have all the facts to decide whether the harms outweigh the real benefits.

Instead of protecting women from screening, it’s time to start saving women’s lives.

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