August 16, 2006

Breast cancer chemo side effects elevated

By Lisa Richwine

WASHINGTON -- Chemotherapy drugs may cause more serious side effects for breast cancer patients under age 64 than once thought, a U.S. study released on Tuesday said.

Researchers mined insurance claims for 3,526 women who had intravenous chemotherapy for breast cancer and tallied problems serious enough to require emergency care or a hospital stay.

Their review found more than 8 percent of women underwent treatment for a fever or infection compared with less than 2 percent reported in an earlier review of clinical trials.

Other problems also occurred more frequently than previously estimated, said the study by researchers at Harvard Medical School and the Dana-Farber Cancer Institute.

For example, 5.5 percent of women were reported to have low blood counts that could raise the risk of infection or bleeding, the new study showed. The rates were less than 1 percent or 2 percent in clinical trials.

Overall, 16 percent of women in the new study had at least one of eight side effects that required emergency care or hospitalization. Side effects also included blood clots, dehydration, nausea and diarrhea. All of the women were 63 or younger.

Researchers did not see any evidence that the side effects shortened lifespan, lead author Dr. Michael Hassett said.

But the findings could help women individually weigh the risks versus their chances of benefit. Not all women are helped by adding chemotherapy to surgery and other measures.

"Our results don't change the benefits of chemotherapy. ... We still think chemo can improve survival" for many women, said Hassett, a researcher at Dana-Farber's Center for Outcomes and Policy Research.

The women in the new study were treated with various intravenous drugs in families known as alkylating agents, anthracyclines, taxanes and anti-metabolites. The information came from claims filed between 1998 and 2002, before some newer drugs were available.

Chemotherapy's side effects can be minimized through steps such as prescribing blood-cell-boosting drugs or nutritional supplements, said Dr. Edgar Staren, chief medical officer at Cancer Treatment Centers of America.

"It's important we make sure (patients) know the various options available," said Staren, immediate past president of the American Society of Breast Surgeons.

The study was funded by the Agency for Healthcare Research and Quality, part of the Department of Health and Human Services, and published in the Journal of the National Cancer Institute.