Adjuvant radiotherapy versus observation following lumpectomy in ductal carcinoma in-situ: A meta-analysis of randomized controlled trials.

The role of adjuvant radiotherapy (RT) following lumpectomy for ductal carcinoma in-situ (DCIS) was addressed in four major randomized controlled trials (RCTs) which were conducted two to three decades ago. Initial results of these trials suggested the protective role of RT in reducing the ipsilateral breast recurrences. Long-term results of all these four trials, based on more than 10-years follow-up data, have recently been published. A meta-analysis of four published RCTs which have addressed the role of adjuvant RT following lumpectomy for DCIS was conducted. Review manager (Cochrane Collaboration's software) version RevMan 5.2 was used for analysis. Evaluated events were ipsilateral breast recurrences (both DCIS and invasive), regional recurrences, contralateral breast events, distant recurrences, and overall mortality. The events were entered as dichotomous variable. The present meta-analysis included four RCTs and a total of 3680 patients - 1710 received adjuvant RT following lumpectomy while 1970 patients did not receive any adjuvant treatment. Patients who received RT had almost half of risk of ipsilateral breast recurrence (RR = 0.53, 95% CI = 0.45-0.62) and regional recurrence (RR = 0.54, 95% CI = 0.32-0.91) compared to those who did not receive adjuvant treatment - there was absolute risk reduction in 15% (95% CI = 12%-17%) for ipsilateral breast recurrences in adjuvant RT treated patients. There was no significant difference in distant recurrence (RR = 1.06, 95% CI = 0.74-1.53), contralateral breast events (RR = 1.22, 95% CI = 0.98-1.52) and overall mortality (RR = 0.93, 95% CI = 0.79-1.09). Though addition of postoperative RT to lumpectomy does not reduce overall mortality, the present meta-analysis confirms that it decreases the ipsilateral breast and regional recurrence by almost half.