Partial Breast Irradiation Compared with Whole Breast Irradiation: A Systematic Review and Meta-Analysis.

Abstract

Early stage-breast cancer is among the most common cancer diagnoses. Adjuvant radiotherapy is an essential component of breast conserving therapy, and several options exist for tailoring its extent and duration. This study assesses the comparative effectiveness of partial breast irradiation (PBI) compared with whole breast irradiation (WBI). A systematic review was completed to identify relevant randomized clinical trials (RCTs) and comparative observational studies. Independent reviewers working in pairs selected studies and extracted data. Randomized trial results were pooled using a random effects model. Prespecified main outcomes were ipsilateral breast recurrence (IBR), cosmesis, and adverse events (AEs). 14 RCTs and 6 comparative observational studies with 17,234 patients evaluated the comparative effectiveness of PBI. PBI was not significantly different from WBI for IBR at 5 years (RR 1.34 [95% CI, 0.83-2.18]; high strength of evidence [SOE]) and 10 years (RR 1.29 [95% CI, 0.87-1.91]; high SOE). Evidence for cosmetic outcomes was insufficient. Significantly fewer acute AEs were reported with PBI compared to WBI, with no significant difference in late AEs. Data from subgroups according to patient, tumor, and treatment characteristics were insufficient. Intraoperative radiotherapy was associated with higher IBR at 5, 10, and >10 years (high SOE) compared to WBI. Ipsilateral breast recurrence was not significantly different between PBI and WBI. Acute AEs were less frequent with PBI. This evidence supports the effectivness of PBI among selected patients with early-stage, favorable risk breast cancer who are similar to those represented in the included studies.