Intraoperative Radiotherapy Versus Whole-Breast External Beam Radiotherapy in Early-Stage Breast Cancer: A Systematic Review and Meta-Analysis

There has not been a clear answer about the efficacy of intraoperative radiotherapy (IORT) for women with early-stage breast cancer. The aim of this meta-analysis was to summarize the available evidence comparing the efficacy and safety of IORT with those of whole-breast external beam radiotherapy (EBRT) for women with early-stage breast cancer. MEDLINE, EMBASE, the Web of Science, and the Cochrane Library were searched up to October 2014. Two authors independently conducted the literature selection and data extraction. Studies that compared IORT with whole-breast EBRT were included in the systematic review. IORT was defined as a single dose of irradiation to the tumor bed during breast-conserving surgery rather than whole-breast irradiation. Qualities of RCTs were evaluated according to the PEDro scale. Qualities of non-RCTs were evaluated according to the Methodological Index for Non-Randomized Studies (MINORS). The risk ratios (RRs) of ipsilateral breast tumor recurrence, overall mortality, breast cancer mortality, non-breast cancer mortality, and distant metastasis were pooled using a random-effects model. Four studies with 5415 patients were included in this meta-analysis, including 2 randomized controlled trials (RCTs) and 2 non-RCTs. Ipsilateral breast tumor recurrence was significantly higher in patients with IORT compared to those with whole-breast EBRT (RR 2.83, 95% CI 1.23–6.51), but with significant heterogeneity (I(2) = 58.5%, P = 0.065). Comparing IORT with whole-breast EBRT, the pooled RRs for overall mortality, breast cancer mortality, non-breast cancer mortality, and distant metastasis were 0.88 (95% CI: 0.66–1.17), 1.20 (95% CI: 0.77–1.86), 0.76 (95% CI: 0.44–1.31), and 0.95 (95% CI: 0.61–1.49), respectively. IORT had a significantly higher risk of ipsilateral breast tumor recurrence than whole-breast EBRT. Overall mortality did not differ significantly. IORT should be used in conjunction with the prudent selection of suitable patients. It is imperative to identify women with a low risk of local recurrence.