There are two reasons why this study shows such different results in the effectiveness of mammograms: first, better treatments such as tamoxifen — a drug that significantly reduces breast cancer mortality — reduce the importance of finding tumors so early. This decreases the importance of early detection methods such as mammograms. Second, in previous studies, women were less aware of the dangers of breast cancer and were therefore more likely to ignore and lumps in their breasts.
Although the study showed no evidence of the positive effects of mammograms, it did in fact show negative ones. One big problem is false negatives; one study showed that 61 percent of women who began having yearly mammograms at age 40 had at least one false positive by age 50. Another study showed that for every real positive resulting from a mammogram, 50 false positives were obtained. Another related problem that has arisen is overdiagnosis: many tumors that are labeled as breast cancer could in fact be quite harmless, meaning that treatment is unnecessary. This leads to dangerous and avoidable treatments and procedures, and extremely high medical expenses. In the U.S., about 37 million mammograms are performed each year, costing approximately $370 million.
This recent literature on the overuse of mammograms has prompted the American Cancer Society to release new guidelines concerning mammograms, which will have the potential to decrease medical costs, reduce the number of unnecessary mammograms, and implement safer screening schedules for women. The new guidelines suggest that women with an average risk of breast cancer should not start having annual mammograms until age 45, and then switch to biennial mammograms at age 55. The American Cancer Society also stated that women should not be receiving clinical breast exams any longer. The United States Preventive Services Task Force took an even more controversial stance by saying that screening women under 50 should receive a rating of "C" in terms of health care, meaning that the service would not be covered by the Affordable Care Act. These new regulations will undoubtedly be extremely controversial, for both physicians and patients, especially since the suggestions are much more relaxed than they were in the past. Evidence shows that once physicians are trained to be more invasive and aggressive in their use of treatments and procedures, it is very difficult for them to take a less active stance. Some believe that using a more cautious method of treatment will increase the likelihood of a lawsuit, others are motivated by financial incentives, and still others simply think that being more aggressive in treatment produces better results.