Obese Women and Chemotherapy
Overweight women are at disadvantage when it comes to chemotherapy, as per findings from a new study published in the Archives of Internal Medicine.
Overweight and obese women with breast cancer often receive intentionally reduced doses of adjuvant chemotherapy. The researchers emphasis that "administration of initial and overall full weight-based doses of adjuvant chemotherapy in overweight and obese women is likely to improve outcomes in this group of patients."
The researchers performed a retrospective cohort study of 9672 women treated with doxorubicin hydrochloride and cyclophosphamide between 1990 and 2001. The main goal of the study was to measure the quality of chemotherapy as measured by the use of reduced doses for the first treatment, the overall dose proportion (actual-expected dose ratio), and relative dose intensity.
Women who are 20 to 25 percent over their ideal body weight have a 1.3 times greater risk of a recurrence of breast cancer, according to background information in the article. Differences in body chemistry in overweight and obese women, including differences in estrogen and insulin levels, may account for their poorer prognosis, but, the authors suggest, there is evidence that inadequate doses of adjuvant chemotherapy may also contribute to the differences in outcome. Adjuvant chemotherapy is given to women with no measurable spread of the cancer beyond the primary tumor to improve the likelihood of disease-free and overall survival. Physicians may deliberately reduce dosage levels, which are calculated on the basis of body weight, for heavier women because of fears of toxic effects, the authors write.
"However, given the evidence that maintaining dose intensity improves the likelihood of overall and disease-free survival and the lack of data supporting dose reductions in overweight and obese women, it is likely that the practice variations we have observed represent 'unwarranted variation' in the adjuvant treatment of patients with breast cancer," the authors write. "The incidence of obesity, particularly severe obesity, is increasing in the United States. Eliminating unwarranted dose reductions will therefore become increasingly important in defining best practices for the care of overweight and obese women."