Retrospective analysis of factors driving breast cancer chemotherapy dose reduction

A retrospective analysis among Kaiser Permanente Northern California patients with stage I-IIIA breast cancer (2006-2013) investigated factors driving chemotherapy dose reduction. Of 452 patients treated with cyclophosphamide plus doxorubicin followed by paclitaxel, 8% received a first cycle dose proportion less than 90%, and 21.2% had an average relative dose intensity less than 90%. In adjusted logistic regression models, obese women had 4.1-fold higher odds of receiving an ARDI less than 90% when compared to normal weight women ( p-trend=0.0006). Increasing age was positively associated with an ARDI less than 90%, as was the presence of comorbidity. Dose reduction was less common in later calendar years. Larger studies are required to evaluate relevance to other regimens, and further work will be needed to determine whether dose reductions impact outcomes in obese women.