Breast Cancer Rate Declines
Breast cancer incidence among U.S. women dropped by 7% from 2002 to 2003, possibly because of a decrease in hormone replacement therapy usage, according to a study presented Thursday at the 29th Annual San Antonio Breast Cancer Symposium, the New York Times reports (Kolata, New York Times, 12/15).
Peter Ravdin, a research professor in the Department of Biostatistics at M.D. Anderson Cancer Center, and colleagues examined records from nine regions across the U.S. that supply data to the National Cancer Institute's Surveillance Epidemiology and End Results.
According to the study, age-adjusted breast cancer incidence decreased by 7% by the end of 2003, compared with 2002 (M.D. Anderson release, 12/14). There were about 124 breast cancer cases per 100,000 women in 2003, compared with about 134 cases per 100,000 women in 2002, the AP/Forbes reports.
Breast cancer incidence decreased by 6% in the first half of 2003 and by 9% in the second half of the year (Marchione, AP/Forbes, 12/15). The study found that breast cancer rates dropped by 15% among women ages 50 and older (Peres, Chicago Tribune, 12/14).
The study -- which was funded by NCI and M.D. Anderson -- concluded that about 14,000 fewer women were diagnosed with breast cancer in 2003 than 2002. The decline in incidence was the largest since 1990, according to the researchers.
According to researchers, the decrease in breast cancer rates is most likely associated with a drop in both HRT use and mammography rates (Gellene, Los Angeles Times, 12/15). According to the Wall Street Journal, HRT use decreased by about 30% in 2002 after the Women's Health Initiative found that breast cancer risk increased for women who used the treatment for an extended period of time.
In addition, mammography rates between 2000 and 2003 dropped by 1% overall and by 3% among women between ages 50 and 64, which could in part explain why fewer breast cancer cases were detected, according to the Journal (Parker-Pope, Wall Street Journal, 12/15). Ravdin said that it is possible that other factors -- including anti-estrogen drugs, such as raloxifene; statin drugs that reduce cholesterol; or drugs used to treat pain -- also might have contributed to the decrease (Chicago Tribune, 12/14).
Although the study does not prove a causal link between the drop in breast cancer rates and HRT usage, it is the only plausible explanation, Rowan Chlebowski of the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center and co-author of the study, said, adding, "To have this kind of drop in cancer rates you need something very big to explain it" (Los Angeles Times, 12/15).
According to the Journal, it is possible certain types of cancer would have developed faster with continued hormone use but still will eventually develop.
Donald Berry, head of the division of quantitative sciences at M.D. Anderson and co-author of the study, said, "It's quite likely that some of these tumors have just been slowed and that we're going to see a boost in incidence in the next few years," adding, however, that "[t]here may be some tumors that actually stop growing because the only thing they were living on was the fuel of the hormones."
Ravdin said, "The long-term impact [of the study] is going to be something that will take another five years to completely understand."
According to the Journal, additional analyses from the WHI study, as well as breast cancer data from other countries, are expected to help explain the decrease (Wall Street Journal, 12/15).
Several broadcast programs reported on the study:
- ABCNews' "World News Tonight": The segment includes comments from Clifford Hudis, chief of the breast cancer medicine service and associate attending physician at Memorial Sloan-Kettering Cancer Center, and Eric Winer, director of the Breast Oncology Center at Dana-Farber Cancer Institute (McKenzie, "World News Tonight," ABCNews, 12/14). Video of the segment is available online.
- CBS' "Evening News": The segment includes comments from Ravdin, Freya Schnabel, professor of clinical surgery at Columbia University Medical Center; and U.S. women (Alfonsi, "Evening News," CBS, 12/14). Video of the segment is available online.
- NBC's "Nightly News": The segment includes comments from Berry and U.S. women (Bazell, "Nightly News," NBC, 12/14). Video of the segment is available online.
- NPR's "Morning Edition": The segment includes comments from Winer (Montagne, "Morning Edition," NPR, 12/15). Audio of the segment is available online.