Aug. 2, 2002 -- Confused by all the controversy over annual mammograms? Here's the bottom line: They work.
A huge new study shows that annual mammograms can reduce breast cancer deaths in women by 40% to 45%.
Study co-author Robert A. Smith, MD, tells WebMD, "This is detailed medical data on a third of the female population of Sweden over several decades. It is a very substantial, population-based analysis. It shows that a woman who actually gets annual mammograms has a 45% lower chance of dying of breast cancer." Smith is director of cancer screening for the American Cancer Society.
The study appears in the Aug. 1 issue of the medical journal Cancer. It compared breast cancer death rates in the mammography era to those in the era before screening. Overall, there were 30% fewer breast cancer deaths among women who had access to mammograms. Among those who actually had annual mammograms, there were 40% to 45% fewer breast-cancer deaths.
Stephen A. Feig, MD, is director of breast imaging at New York's Mount Sinai Hospital and is professor of radiology at Mount Sinai School of Medicine. His editorial comments appear alongside the study.
"Are the results of this study unassailable? I say 'Yes,'" Feig tells WebMD. "But that doesn't mean the results won't be assailed by some. Mammography is not a perfect test, but it is the best test we have, and the benefits certainly outweigh the risks."
A study published last year claimed that clinical trials of mammography were flawed. It suggested that there was no reliable evidence that mammography saves any lives at all.
"They were wrong," Feig says. "Every single U.S. medical society has criticized that article and says that we should screen women. The Swedish board of health rejected that finding, and so did the World Health Organization. Yet it is like getting up in a theatre and screaming, "Fire!" Even if there is no fire, some people are going to believe you and panic."
If anything, Feig says, clinical trials of mammograms underestimate their value. This is because of their strict rules. A woman is counted as screened if she is assigned to the screening group -- whether or not she actually got mammograms. And women assigned to the group that does not get screened often seek mammograms outside of the trial. Feig says as many as 30% of women assigned to the "no screening" group may do this.
Nevertheless, Smith acknowledges that there are downsides to mammography. The main problem is that mammograms sometimes find lesions that -- after biopsy -- turn out to be harmless. Another problem is overaggressive treatment.
"Some people want to describe these downsides as harms, some say limitations," Smith says. "Sometimes treatment is more aggressive than it should be, but that is not a problem of screening. Women have an understanding that false positives and less aggressive tumors are just part of the process. The vast majority of things we detect would be life threatening if they weren't treated. Early detection gives women more treatment options."
The bottom line? Feig recommends annual mammograms for all women, beginning at age 40.