Sixteen percent of women who underwent chemotherapy for breast cancer experienced serious adverse effects requiring emergency care or hospitalization, according to a new study supported by the U.S. Department of Health and Human Services’ Agency for Healthcare Research and Quality.

Most of the adverse events were related to serious complications caused by the toxicity of the drugs. These complications, which included anemia, dehydration, and reduced production of white blood cells, also augmented the costs of care.

The odds of experiencing a serious adverse effect increased by 20 percent per month for each additional month of chemotherapy administered to women after their initial breast cancer diagnosis.

“The study highlights the importance of studying how drugs affect people in everyday medical care,” said AHRQ Director Carolyn M. Clancy, M.D. “It is important to know the impact of interventions such as chemotherapy so that patients can make informed decisions about the risks and benefits of their treatment options.”

The study is the first to analyze the risks of serious adverse effects from intravenous chemotherapy in women under age 65 since medications to treat the complications of chemotherapy became more available, the report’s authors said. Expenditures for the hospital and emergency room care of each of the women adversely affected by chemotherapy averaged $10,000 more a year than expenditures for the same services for those women who underwent chemotherapy but did not have a serious complication.

More than 8 percent of the women who had chemotherapy were seen in the emergency room or were hospitalized for infection and fever. The proportion of women treated for other chemotherapy-related problems included:

o Neutropenia or thrombocytopenia -  disorders that reduce the production of white blood cells or platelets -  5.5 percent

o Electrolyte disorders such as dehydration -  2.5 percent

o Nausea or diarrhea -  2.4 percent

o Fatigue, dizziness and related conditions -  2 percent

o Deep venous thrombosis or Pulmonary embolism -  1.2 percent

o Malnutrition -  just under 1 percent

The researchers, who were led by Michael J. Hassett, M.D., with the Harvard-affiliated Dana-Farber Cancer Institute, also found that, for chemotherapy patients who had adverse events, their annual medical expenditures for all causes 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 than did the expenditures for the chemotherapy patients who did not experience serious complications.

Details are in “Frequency and Cost of Chemotherapy-Related Serious Effects in a Population Sample of Women with Breast Cancer,” published in the August 16 issue of the Journal of the National Cancer Institute.

Agency for Healthcare Research and Quality (AHRQ)