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Aug. 15, 2006 -- The potentially serious side effects of chemotherapy appear to be greater for younger breast cancerbreast cancer patients than clinical trials suggest, according to findings from a new study.
Sixteen percent of the breast cancercancer patients in the study who had chemotherapy experienced serious adverse chemotherapy-related health events that resulted in hospitalization or an emergency visit to the hospital.
More than 8% of chemotherapy patients were treated for infection or fever. Data from clinical trials suggest that just 1% to 2% of patients experience this chemotherapy side effect, researcher Michael J. Hassett, MD, MPH, tells WebMD.
Underestimating the Risk
All of the women included in the study were aged 63 or younger when they were diagnosed with breast cancer.
"All of our previous estimates of chemotherapy side effects among women of this age group have come from clinical trials [designed to assess new drugs]," Hassett says. "We hypothesized that the risk estimates generated in these trials may be too low."
More women have chemotherapy for breast cancer than for any other cancer, and chemotherapy is a leading cause of serious and even life-threatening adverse health events.
Only one previous study has examined the frequency of chemotherapy-related serious side effects in the general population of women treated for breast cancer, and that trial included only women over age 65.
Hassett and colleagues from Harvard Medical School's Dana-Farber Cancer Institute sought to better understand the frequency of chemotherapy-related hospitalizations and ER visits among younger women in their latest study, published in the Aug. 16 issue of the Journal of the National Cancer Institute.
Chemo Side Effects
Using a medical insurance claims database, the researchers compared outcomes within the first year of treatment among 3,526 newly diagnosed breast cancerbreast cancer patients 63 years or younger treated with chemotherapy and an equal number of patients with similar characteristics who did not receive chemotherapy.
Sixty-one percent of chemotherapy patients were hospitalized or were treated at hospital ERs during their first year of treatment, compared with 42% of the patients treated without chemotherapy.
In addition to the larger than previously reported treatment for fever and infections, the researchers documented a higher than previously reported incidence of other chemotherapy-related side effects, including: low white blood cell or platelet counts (5.5% of patients); dehydrationdehydration and other electrolyte (such as sodium and potassium) disorders (2.5%); nausea, vomiting, or diarrheadiarrhea (2.4%); general symptoms such as fatiguefatigue (2%); and serious blood clots (1.2%).
Compared with chemotherapy patients who did not have treatment-related serious adverse events, medical costs for those who did averaged $13,000 more for hospital care, $406 more for emergency room visits, $16,000 more for outpatient care, and $1,900 more for prescription drugs.
'More Suffering, Higher Costs'
"Our results suggest that breast cancercancer chemotherapy may cause more patients suffering and higher health care costs than previously estimated," the researchers wrote.
Hassett says the findings point to the importance of doing a better job of assessing serious chemotherapy-related side effects so that breast cancer patients and their doctors can better understand the risks vs. benefits of this treatment.
John K. Erban, MD, who directs the breast cancer program at Tufts New England Medical Center, agrees.
"It is not likely that this research will change practice in terms of whether clinicians recommend chemotherapy to their patients," he tells WebMD. "But it can help us better advise our patients so that they will be better prepared."
In an editorial accompanying the study, Erban and Tufts colleague Joseph Lau, MD, wrote that tracking the long-term side effects of chemotherapy will become especially important as drug treatment for breast cancer enters a new era of targeted therapy.
While in the short term the newer drugs have proven to be much less toxic than traditional chemotherapy, the long-term side effects of the treatment are not known.
"We don't know what the long-term implications of giving one of these therapies followed by another and then maybe another will be," he says.
SOURCES: Hassett, M.J. Journal of the National Cancer Institute, Aug. 16, 2006; vol 98: pp1108-1117. Michael J. Hassett, MD, MPH, Center for Outcomes and Policy Research, Dana-Farber Cancer Institute, Boston. John K. Erban, MD, director, Breast Cancer Program, Tufts New England Medical Center, Boston.