Women with breast cancer who are obese or less educated are twice as likely to get reduced doses of chemotherapy than doctors recommended, jeopardizing survival, according to scientists at the University of Rochester Medical Center. The results will be published in the Jan. 20 issue of Journal of Clinical Oncology.
The research focused on 764 women enrolled in the Awareness of Neutropenia in Chemotherapy Study Group Registry, which is based at Rochester's James P. Wilmot Cancer Center. The women received treatment between 2002 and 2005 at 115 randomly selected, private oncology practices around the country.
According to researchers, 21 percent of obese and severely obese women received less than 85 percent of the standard dose, compared to less than 10 percent for lean women. More than 32 percent of women who didn't finish high school saw chemotherapy reduced, compared with 14 percent of high school or college-educated women.
"Simply put, this evidence shows that doctors are likely to reduce the chemotherapy levels for these women, even though there is no solid medical basis to do it," said Gary Lyman, M.D., M.P.H., principal investigator and director of the ANC Study Group, an Amgen-funded project that leads multi-center studies of cancer patients starting chemotherapy. The University of Rochester Medical Center funded this retrospective study.
Frequent under-treatment with chemotherapy is a well-documented problem. Oncologists are sometimes reluctant to deliver full doses of chemotherapy to an obese woman, despite the calculations based upon her weight that indicate it is appropriate and safe. There are also studies that point to wide variations in oncology practice between different regions of the country.
In this study, Rochester researchers reviewed the records of the women enrolled in the ANC Study Group Registry and analyzed detailed information on patients' age, education, insurance coverage, zip code, height, weight, treatment plan and actual chemotherapy received. They measured this data against U.S. Census Bureau information on each geographic area. They also calculated the standard chemotherapy dose that should be delivered to each patient and compared it to the actual dose each woman received.
The results are familiar to Lyman and his research team. He has published studies that showed less than half of patients with breast cancer and non-Hodgkin's lymphoma receive full doses of chemotherapy.
The treatment disparities for women with different body mass index and education levels concern Lyman. He said it appears some doctors anticipate patients with less education will have trouble tolerating chemotherapy treatment and reduce the doses.
"This whole issue of dose intensity is a major indicator of quality in cancer care and it must be addressed," Lyman said. "We have new therapies and cures out there for many forms of cancer and sadly, sometimes we're not curing people because they are not getting the full doses that should be standard."
This year, more than 200,000 women in the U.S. will be diagnosed with breast cancer. About 41,000 women will die from the disease, according to the American Cancer Society.
Journal
Journal of Clinical Oncology