Breast cancer adjuvant chemotherapy dosing in obese patients: dissemination of information from clinical trials to clinical practice.

BACKGROUND

Substantial variation in adjuvant breast cancer chemotherapy dosing in obese women suggests that there is uncertainty about optimal practices. The purpose of this study was to investigate variations in dose determinations in clinical trial protocols and publications over the last 3 decades as potential sources of this uncertainty.

METHODS

The National Cancer Institute database was used to identify protocols of breast cancer adjuvant chemotherapy conducted by cooperative groups between 1970-2000, and these protocols were then obtained directly from the cooperative groups. Dose determinations were categorized in each protocol and in published reports from each clinical trial. Fisher exact tests were used to compare the proportions of protocols that used full weight-based doses over time.

RESULTS

Protocol-specified chemotherapy dosing was obtained for all of 44 eligible trials. A significant increase was identified in the use of full weight-based doses in the later time period compared with the earlier (P = .004; 2-sided Fisher exact test). A notable exception was 1 cooperative group that continues to require dose limitations for doxorubicin and cyclophosphamide in patients with a body surface area of more than 2.0 m(2). Regardless of publication date, published reports of clinical trials rarely provide information on use of full or limited weight-based doses.

CONCLUSIONS

Variations in dose determinations among clinical trial protocols and lack of information on use of full weight-based doses in most publications are 2 likely sources of variation in chemotherapy dosing in obese women. Developing consensus and disseminating information on optimal chemotherapy dosing will likely reduce such variation and may improve survival among obese patients with breast cancer.