Our expert is Karla Kerlikowske, MD, Staff Physician, Medical Service, San Francisco Veterans Administration Medical Center, Professor of Medicine and Epidemiology and Biostatistics, University of California at San Francisco.
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When you screen a healthy population for breast cancer, you’re going to get over-diagnosis. This has become particularly evident. As screening practices switched from film-based mammography to digital mammography, we now can detect more small lesions. Only some of those small lesions that we are now detecting will grow into aggressive cancers. For 10-30% of the cases we find a lesion, we don’t necessarily need to cut it out or radiate it; we could follow it to see if it increases in size in a short period of time. Overdiagnosis is particularly important for older women to consider. What we don’t want is for the elderly woman to feel traumatized by being treated for an indolent lesion when that treatment will not prolong her life, but will increase her anxiety. And once she’s had lumpectomy and radiation for an indolent lesion, she’ll have follow-up tests for the rest of her life. Overdiagnosis means that she’s likely to endure all this for a condition that might cause her very little trouble during the rest of her life, if it hadn’t been detected.
TO AVOID OVERDIAGNOSIS, ONLY DO RISK-BASED SCREENING
At the Breast Cancer Surveillance Consortium, we’ve developed the free BCSC Risk Calculator, which can be accessed from https://tools.bcsc-scc.org/bc5yearrisk/calculator.htm and downloaded . It’s also available for download to your iPhone from https://itunes.apple.com/us/app/bcsc-risk-calculator/id919034661?mt=8.
One of the goals of the Risk Calculator is to encourage health care providers to assess a woman’s risk before deciding to screen for breast cancer. We now know that it’s common for women to over- or underestimate breast cancer risk. With this tool, health care providers will have a much more accurate picture of a woman’s individual risk and can then delay screening to a later age and/or screen those who are at low risk for breast cancer less often. Instead of merely going by age, as we’ve done in the past, we can now also take into account the individual’s ethnicity, breast density, whether she’s had a first-degree relative with breast cancer, and whether she’s had a breast biopsy, and if so, the breast biopsy outcome. The Risk Calculator is free, simple, easy-to-use, and can decrease the risk of overdiagnosis by tailoring screening to a woman’s risk of breast cancer.
WE NEED A NEW PARADIGM FOR RESPONDING TO SMALL LESIONS
As it is, all small lesions are biopsied to determine if they are cancer. However, some lesions put women at risk for breast cancer, but are not themselves cancer, in the same sense that moderate hypertension is a risk factor for stroke, but hypertension is a condition, not a disease. Whether it’s a small lesion or moderate hypertension, the symptoms bear watching, but they’re symptoms, not the disease itself that requires aggressive treatment. Research is underway to monitor small lesions rather than removing all of them.
LIFESTYLE MODIFICATIONS ARE IMPORTANT FOR PREVENTING BREAST CANCER
The data are clear: if a woman is overweight or obese and reduces her weight, she’ll reduce her risk of breast cancer.
The data are also clear that exercise is important for risk reduction. She needs to be physically active for at least 20 or 30 minutes for 5 to 7 days per week. A brisk walk is good, taking the stairs, and vigorous housework such as gardening, vacuuming or sweeping will also help. Her goal should be movement as opposed to just sitting.
As for diet, there aren’t enough large-scale diet studies to allow us to say which diet is most protective against breast cancer. A Mediterranean Diet, one that’s high in fruits, vegetables, whole grains, legumes, and nuts, seems to hold some promise, but we aren’t in a position right now to be sure. What we do know is: if your patient is overweight, she needs to consume fewer calories, and whether she’s overweight or not, she needs to exercise 5 to 7 days a week.