Are Breast Cancers Detected by Mammography Different?
April 24, 2000 -- Screening mammography detects breast cancers very early, which then have an excellent prognosis. This excellent prognosis may be due not just to early detection, but also to the fact that many of the cancers detected are not aggressive in nature and may therefore not require aggressive therapy, a study in the April 24 issue of the Archives of Internal Medicine concludes.
"The [purpose] of our study is to alert physicians and perhaps patients that everything that looks like cancer under the microscope may not behave like cancer," study author Alvan Feinstein, MD, MS, tells WebMD. Feinstein is professor of epidemiology at Yale University School of Medicine. "These [early-stage] cancers certainly do not need radical treatment. We must simply be aware that they exist and may eventually need other types of treatments."
"This paper identifies one of the raging arguments about mammography in general," says Roy Smith, MD, director of medical oversight for the National Surgical Adjuvant Breast Project (NSABP) in Pittsburgh. "That is, are we simply moving the time of diagnosis further back to an earlier point in the disease, so it makes it appear that women diagnosed with mammography are living longer? And are we identifying tumors that would have disappeared on their own or simply grown very slowly? My thought is mammography is the only tool we have at the present time, and we know that a physical exam alone is not good enough."
Feinstein and colleagues studied over 200 patients who were diagnosed with breast cancer for the first time in 1988. Factors such as age, stage of breast cancer, type of therapy, and how the patients were diagnosed were identified. Those patients who were diagnosed by screening mammography had earlier-stage disease and were less likely to either die of breast cancer or experience a recurrence than patients diagnosed by a different method.
The authors suggest that understanding more of the biological behavior of these tumors could be useful in managing breast cancer therapy. "If many of the cancers are indeed relatively benign, they can be treated less aggressively than in the past," the authors say. Feinstein adds, "Less aggressive treatment would include lumpectomy [removal of the tumor alone] and watchful waiting. There is a place for mammography in following these patients as well."