7. long-term toxicity after postmasieciomy radiation and doxorubicin-based chemotherapy

Purpose: To assess the incidence of long-term loxicities after postmastectomy radiation and doxorubicin-based adjuvant chemotherapy. Methods: Records of 470 patients treated with mastectomy, doxorubicin-based chemotherapy, and postmastectomy radiation in five institutional prospective trials were retrospectively reviewed. Actuarial toxicity rates were compared to those of 1, 031 patients treated with mastectomy and doxorubicin-based chemotherapy who did not receive postmastectomy radiation. The chest wall received a median dose of 55 Gy with Co-60 (42%) or electrons (51%). Adjuvant chemotherapy consisted of a doxorubicin-based regimen, often followed by two years of cyclophosphamide, methotrexate and fluorouracil. Results: Median follow was 10 years. The overall 10-year actuarial rates of RTOG toxicity grade 1 and 3 resulting after radiation were 4% and 2%, respectively. The overall 10- and 15-year actuarial rates of second non-breast cancer malignancy were 3.8% and 7%, respectively. There was no statistical difference between the rates of non-breast cancer second malignancy in the radiated and unirradiated cohorts (3.4% vs. 4.7% 10-year actuarial rates). Increasing age and treatment with 10 cycles of chemotherapy were associated with higher rates of second malignancy (P = .025, P = .016). The 10-year actuarial rate of cardiac death was 2.4% (8 events) and 0.5% (5 events) in the radiated and unirradiated groups respectively (P = .058). Only 2/8 cardiac deaths in irradiated patients had left-sided treatment. Conclusions: We found ver)- low rates of serious sequelae after postmastectomy radiation. The rate of second non-breast cancer malignancy was increased among patients treated with 10 cycles of cyclophosphamide-containing chemotherapy.