Breast-conserving surgery and radiotherapy for ductal carcinoma in situ of the breast: Meta-analysis of randomized controlled trials

The addition of radiotherapy (RT) to breast-conserving surgery (BCS) is common clinical practice in the treatment of patients with ductal carcinoma in situ (DCIS). The objective of this meta-analysis is to assess the cumulative evidence of the benefit of RT in this situation. The analysis includes all available English-language randomized controlled trials (RCT) comparing outcomes in patients who received BCS alone and those who received BCS and RT. Only 4 eligible RCTs were identified. Statistical analysis was carried out to compare relative and absolute risk of mortality, as well as ipsilateral, contralateral and total recurrence of either DCIS or invasive disease. Heterogeneity between trials was assessed. A reduction in total breast cancer recurrence was observed, with a pooled estimate of an absolute risk reduction of 10% (95% CI 7–14%) and a relative risk reduction (risk ratio) of 0.66 (95% CI 0.54-0.79) in the intervention arms of all 4 trials. There was significant intertrial heterogeneity in these estimates. The reduction was due primarily to a reduction in ipsilateral recurrence in patients treated with RT as well as BCS compared to those receiving BCS alone. There was no significant reduction in overall mortality between BCS and BCS+RT groups across all 4 trials, and no significant heterogeneity was observed. Potential sources of bias were identified that point to the need for further analysis and should inform future trials.