The effect of postoperative radiotherapy on the feasibility of optimal dose adjuvant CMF chemotherapy in stage II breast carcinoma

The impact of a number of variables upon the effectiveness of adjuvant chemotherapy given to 87 patients with Stage II breast carcinoma was retrospectively analyzed. Adjuvant chemotherapy consisted of cyclophosphamide, methotrexate and 5-fluorouracil (CMF). Drugs were given in optimal doses (85% or more of the planned dose) to 17% of the patients; in intermediate doses (66 to 84% of the planned dose) to 50% of the patients; and in low doses (65% or less of the planned dose) to 33% of the patients. Myelosuppression was the main reason for giving intermediate or low doses. At a median follow-up of three years, 84% of all patients remain alive. Radiation therapy preceding chemotherapy was given to 70 % of the patients, concomitant irradiation and chemotherapy to 15 %, and 13 patients (15%) received chemotherapy only. Of the 14 patients who received optimal doses of CMF, 12 (86%) also received radiation therapy. Disease-free survival at three years is similar for irradiated and nonirradiated patients, but the latter have a higher incidence of local recurrence (5 % vs. 15 %), although the difference is not statistically significant. Delay in the initiation of chemotherapy, mostly because of the administration of postoperative irradiation, adversely affected the probability and duration of disease-free survival, particularly in premenopausal women in whom chemotherapy was started within more than 90 days of mastectomy. The administration of optimal doses of adjuvant chemotherapy should follow the primary treatment to the breast tumor as closely as possible. If radiation therapy is indicated as well, it should be delivered concomitantly with chemotherapy, given the feasibility of administering both modalities simultaneously, as demonstrated in this study.