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Side Effects Limiting Chemotherapy
April 28, 1999
WASHINGTON (AP) - Side effects may prevent up to one-fifth of breast cancer patients from getting the full-strength dose of chemotherapy needed for their best chance of survival, says a study of the medical records of 15,000 patients.
Doctors prescribe the right amount, but may lower the dose mid-treatment or postpone chemotherapy sessions when women suffer serious side effects, the research found.
The findings may surprise doctors unaware that some efforts to ease side effects could have a larger impact.
Switching to a newer combination of chemotherapy drugs could give patients a better chance at tolerating the full dose, contends Dr. Garrett A. Smith of the University of California, San Francisco, whose patients were among those the study analyzed.
"This study should change practice patterns," he said. "Physicians all over the country who use the older (chemotherapy) regimen had a terrible time staying on track."
Project ChemoInsight was performed by Amgen Inc., which makes a treatment for a chemotherapy side effect called neutropenia — a loss of white blood cells that leaves patients vulnerable to serious infection.
At issue is "adjuvant chemotherapy" given after breast tumors are surgically removed. Previous studies have found that the women who fare best receive at least 85 percent of the chemotherapy "dose intensity" — proper dose received during a certain amount of time. But side effects can prevent that.
Amgen nurses gathered medical records from hundreds of oncologists to see how often that happens. About 20 percent of patients got less than optimal dose intensity, concludes data to be presented at an Oncology Nursing Society meeting this week.
Neutropenia was the main culprit that prompted dose limiting. Researchers are visiting doctors whose records were analyzed to discuss how their patients fared.
Smith said his patients did well, and credits a newer chemotherapy cocktail known as AC, for adriamycin-cyclophosphamide.
Many doctors believe AC is harder to tolerate than an older cocktail called CMF, but Smith said Project ChemoInsight found CMF patients were more likely to be undertreated because of side effects. He will present details at an oncology meeting next month.
Dr. Claudine Isaacs of Georgetown University in Washington, D.C., called the project important for illustrating what really happens to treated patients.
"There certainly is a perception out there that AC is more toxic," said Isaacs. The study suggests "in fact it's easier to give ... on time and at the dose intended, and that's important."
She already tells patients that AC causes more nausea, but new anti-nausea drugs largely control that. AC also causes more hair loss than CMF and about a 1 percent risk of heart toxicity, but lasts just three months. CMF takes six months, causes mouth sores, diarrhea and may increase risk of premature menopause.