Influence of definitive radiation therapy for primary breast cancer on ability to deliver adjuvant chemotherapy.

Primary radiotherapy as a means of managing stage I and II breast cancer is receiving increasing attention. In a prospectively randomized trial comparing modified radical mastectomy to lumpectomy followed by definitive radiotherapy, we evaluated whether radiotherapy has a deleterious effect on the ability to administer adjuvant doxorubicin and cyclophosphamide to patients with histologically positive axillary lymph nodes. All patients were treated with an identical regimen, and doses were escalated to the same degree until myelosuppression occurred. There were no significant differences in the amount of chemotherapy administered to either treatment group. Patients in both groups received approximately 100% of the predicted dose of doxorubicin and approximately 117% of the predicted dose of cyclophosphamide. At present, we have no evidence that there are differences in recurrence rates as a function of the quantity of drug received, although longer follow-up is required.