Concurrent cyclophosphamide, methotrexate, and 5-fluorouracil chemotherapy and radiotherapy for breast carcinoma: a well tolerated adjuvant regimen

Background: The current study was conducted to assess the toxicity of concurrent adjuvant cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) chemotherapy and radiotherapy (RT) for early breast carcinoma.

Methods: In the current study, the authors reviewed the records of 680 consecutive breast carcinoma patients who received adjuvant CMF at the Princess Margaret Hospital between 1980-1990. Surgery was comprised of mastectomy in 64% of patients, breast conservation in 35% of patients, and was unknown in 1% of patients. Two hundred two patients received concurrent CMF/RT that was defined as an overlap in CMF and RT administration of at least 21 days. Forty-seven patients received sequential CMF/RT (defined as no overlap or an overlap of < 7 days in CMF and RT administration). Other patients received CMF alone. Adverse effects of RT were graded retrospectively using the Radiation Therapy Oncology Group (RTOG)/European Organization for Research and Treatment of Cancer (EORTC) system. Reasons for interruption or failure to complete RT were recorded. The magnitude of chemotherapy dose reductions and delays also were noted.

Results: The median age of the patients was 44 years (range, 26-68 years) and 88% of the patients had lymph node-positive disease. RT was interrupted or discontinued due to side effects in 4% of patients (95% confidence interval [95% CI], 1.7-7.7%) and 0% (95% CI, 0-7.6%), respectively, of the concurrent and sequential groups (P = 0.36). The incidence of Grade 3 or Grade 4 RT toxicity was 1.5% (95% CI, 0.3-4.3%) and 2.1% (95% CI, 0.1-11.3%), respectively, for the concurrent and sequential groups (P = 0.57). The median relative dose intensity of chemotherapy for patients receiving concurrent CMF/RT, sequential CMF/RT, and CMF alone was 0.87, 0.84, and 0.85, respectively (P = 0.22).

Conclusions: The results of the current study demonstrate that the concurrent administration of CMF and RT is associated with a low risk of serious toxicity and is an acceptable adjuvant regimen for patients with breast carcinoma.