NEW YORK (Reuters Health) – Both screening mammography and new drug therapies have played a role in the decline in breast cancer deaths that has occurred over the last three decades, according to a new study, but the relative contributions of each still remain unclear.
The findings, which appear in The New England Journal of Medicine, stem from seven research groups that developed their own statistical models of breast-cancer incidence and mortality and then applied the models to the same set of data. The goal was to determine how much screening mammography and therapies have contributed to the drop in breast cancer mortality in the United States from 1975 to 2000.
Lead author Dr. Donald A. Berry, from M. D. Anderson Cancer Center in Houston, told Reuters Health that one of the main reasons for doing the study was to verify or refute the benefits of screening mammography. "The trials conducted to evaluate the effect of screening mammography on breast cancer mortality have been controversial. So, the question was do the findings from these studies translate into clinical practice."
Although the results varied among the research groups, each of them identified a survival benefit for both screening mammography and drug therapies, including tamoxifen and chemotherapy.
During the study period, breast cancer mortality fell by 21.3 percent, the report indicates. Depending on the statistical model used, screening mammography accounted for 28 percent to 65 percent of this reduction with new drug therapies accounting for the remainder.
"The results showed quantitative differences, but were qualitatively the same," Berry pointed out.
"It is certainly comforting for women to know that the benefits of…therapy from trials translate essentially unchanged into clinical practice. Although we are less certain about the impact of screening, the benefit is almost certainly there," he added.
The findings support the belief that screening mammography saves lives, Dr. D. David Dershaw, from Memorial Sloan-Kettering Cancer Center in New York, notes in a related editorial. He discusses the pros and cons of film versus digital mammography, but concludes that the key message is that eligible women should undergo screening, regardless of the method employed.
The American Cancer Society currently recommends that all healthy women 40 years of age or older undergo mammography each year. Women at increased risk, such as those with a family history or past breast cancer, should discuss with their doctor the benefits and limitations of starting mammograms when they are younger, having additional tests or having more frequent exams.
SOURCE: The New England Journal of Medicine, October 27, 2005.
Source: REUTERS
