Screening, adjuvant therapy both contribute to drop in breast Ca mortality.(News)

For the first time, researchers have separated the survival impacts of screening mammography and adjuvant therapy on breast cancer.

From 1975 to 2000, the overall reduction in breast cancer mortality was 24%. The portion of decrease attributable to breast cancer screening ranged from 28% to 65%, with the remaining portion attributable to adjuvant therapy, said Donald A. Berry, Ph.D., and his colleagues (N. Engl. J. Med. 2005;353:1784-92).

A seven-group research consortium concluded that screening and adjuvant therapy have worked synergistically to contribute to the decrease, said Dr. Berry, who is the chair of the department of biostatistics and applied mathematics at the University of Texas M.D. Anderson Cancer Center in Houston. Other studies have purported to estimate the impact of screening mammography on breast cancer mortality, but none has incorporated the benefits of adjuvant therapy, he said in an interview.

"Comparison of survival for patients detected mammographically versus otherwise is fundamentally flawed for inferring screening benefit," he said. "In population-based studies over different time periods when there were different uses of screening--none versus common--the effects of screening are confounded with other effects of time. And so far, these studies have ignored treatment advances over the time period. We considered both treatment and screening."

Even if screening trials provided clear-cut, indisputable evidence of a mortality benefit, it has remained unclear how those results would translate to the general population. The same can be said about the mortality rates seen in adjuvant therapy trials. The research project has laid that question to rest, Dr. Berry said. "We concluded that the benefits of adjuvant treatment that have been observed in ...