Chemotherapy drugs may cause more serious side effects for breast cancer patients younger than 64 than once thought, according to a study released last week.
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% of women underwent treatment for a fever or infection compared with less than 2% reported in an earlier review of clinical trials.
Other problems also occurred more frequently than previously estimated, according to the study, which was conducted by researchers at Harvard Medical School and the Dana-Farber Cancer Institute.
For example, 5.5% of women were reported to have low blood counts that could raise the risk of infection or bleeding, the study showed. The rates were less than 1% or 2% in clinical trials.
Overall, 16% 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, said lead author Dr. Michael Hassett, a researcher at Dana-Farber's Center for Outcomes and Policy Research.
But the findings could help women individually weigh risks versus 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, Hassett said.
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 insurance 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."
The study was funded by the Agency for Healthcare Research and Quality, and published in the Journal of the National Cancer Institute.