Background: The impact of delaying irradiation to the intact breast for patients receiving chemotherapy for lymph node positive breast cancer is controversial.
Methods: From 1974 to 1989, 474 patients underwent lumpectomy and intact breast irradiation for early stage invasive breast cancer. Chemotherapy was administered to 84 patients (1 patient with bilateral breast cancer) because of positive axillary lymph nodes. Time from definitive breast surgery (lumpectomy or reexcision) to the initiation of breast irradiation was 21-314 days, with a median of 124 days. Forty-two patients began receiving radiation therapy before 120 days (early) and 42 more than 120 days after surgery (delayed). In the early group, cyclophosphamide/methotrexate/5-fluorouracil (CMF) was administered to 32 patients, doxorubicin, cyclophosphamide or cyclophosphamide, doxorubicin, 5-fluorouracil (AC or CAF) to 6 patients, and other regimens to 4 patients; in the delayed group, CMF was given to 29 patients, CAF to 12 patients, and L-PAM/5-fluorouracil to 1 patient.
Results: Median follow-up was 62 months. There was one breast recurrence in the early group, compared with six in the patients receiving delayed irradiation. The actuarial relapse rates for these groups at 5 years were 2% and 14%, respectively (P = 0.05). Survival and distant disease free survival were not significantly different between the two groups.
Conclusions: Delays in the initiation of irradiation are associated with increased risk of relapse in the breast. When possible, the interval between definitive breast surgery (lumpectomy or reexcision) and the initiation of radiation therapy should be fewer than 120 days.