DR. WARNER: Treatment of breast cancer has tremendously improved. Back in the 1960s, we weren’t giving adjuvant therapy to anybody. We were doing surgery and then saying good luck. Now, most women will get some kind of additional treatment, with huge benefits. And it’s possible that 15 per cent mortality reduction due to screening mammography today is even less. So, we don’t really know, and that’s why I think that for women in their 40s it should be between the woman and her doctor to discuss the pros and the cons, and let each individual woman decide if she wants a screening mammogram.
What does the task force mean when it refers to terms like false positives and over-diagnosis?
DR. YAFFE: When screening is done two pictures are taken of each breast. Using those images, about 93 per cent of women can be told they do not have cancer. In the other seven per cent, the radiologist would like the woman to come back for additional images to make absolutely sure there is no cancer. In only about one per cent of those women screened is a needle biopsy performed, and depending on their age, one-quarter to one-third of that one per cent is found to have cancer.
So when women are called back for imaging and don’t have cancer, that’s called a false positive. Certainly, being recalled induces stress. But typically it’s a relatively short-lived stress, and once you have the answer that stress disappears. It would probably be helpful if when women are called back they are informed that there is only about a one in 20 chance they have cancer.
DR. WARNER: From personal experience, having had callbacks for mammograms and biopsies that turned out to be benign, it’s incredibly stressful. There are women who have an abnormal mammogram and then come back months later for an ultrasound or something else. There are more women who have the stress that turns out to be for nothing, than there are women who actually have their cancer diagnosed.
DR. EISEN: The other thing about over-diagnosis is the concept that maybe we’re picking up latent breast cancer that would never clinically cause a problem – much along the lines of the prostate cancer screening issue, where we know there’s a very high prevalence of indolent [slow-growing]prostate cancer.
DR. YAFFE: Part of the challenge of dealing with breast cancer once it’s detected is figuring out which breast cancers are going to be the aggressive ones that really need to be treated aggressively and which ones aren’t. If we could do that – and that’s really the subject of ongoing research – I think it would be possible to do something closer to “watchful waiting.”
What strategy should a woman in her mid-40s, with little knowledge about her breast cancer risk, take?
DR. WARNER: She needs to be what we call “breast aware.” We used to recommend that women do monthly breast self-examination in a very diligent manner. Randomized trials have shown that doesn’t reduce mortality, but that doesn’t mean a woman shouldn’t be able to find lumps as early as possible. She needs to know what her breasts normally feel like, so that if something changes she can say, ‘Hey, that wasn’t there a month ago; I better go see my doctor right away.’
Plus, there are various lifestyle things women can do that are helpful: avoiding hormone replacement therapy if they go into menopause and don’t need it, minimizing alcohol consumption, exercising and keeping their weight down, especially after menopause.
DR. EISEN: Women should really seek out information to find out if they really are average risk, because many women aren’t aware of the full impact, for example, of family history on both sides of the family and other risk factors that may increase their risk of breast cancer. There is a program in Ontario now to start screening with mammography and MRI at age 30 for women who are at very high risk, mostly for hereditary reasons.
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