Secondary malignancies after partial versus whole breast irradiation: a systematic review and meta-analysis

Secondary malignancies are a common complication for patients receiving radiotherapy. Here, we compared rates of secondary malignancies after partial breast irradiation (PBI) and whole breast irradiation (WBI). The MEDLINE, EMBASE, and the Cochrane Library databases were systematically searched to identify relevant randomized clinical trials comparing PBI with WBI in breast cancer patients treated with breast-conserving therapy. Four studies including 2,185 patients were selected. Compared to WBI, the pooled odds ratios (OR) for contralateral breast cancer were 0.86 (95% confidence interval (CI) 0.31-2.42; p = 0.78) after 5 years and 1.15 (95% CI 0.43-3.09; p = 0.78) after 10 years for PBI. The pooled ORs for secondary non-breast cancer were 0.91 (95% CI 0.49-1.67; p = 0.77) after 5 years and 1.20 (95% CI 0.39-3.66; p = 0.75) after 10 years for PBI compared to WBI. These results demonstrate that the risk of secondary malignancies is similar for PBI and WBI after breast-conserving radiotherapy.