Partial breast irradiation versus whole breast irradiation after breast-conserving surgery in early-stage breast cancer: a systematic review

Introduction Adjuvant radiotherapy for early-stage breast cancer has progressively shifted toward less extensive treatment approaches. Partial breast irradiation (PBI) has emerged as a safe and effective option for appropriately selected patients. Aim To systematically compare PBI versus whole breast irradiation (WBI) in early-stage breast cancer with respect to acute and late toxicity, cosmetic outcomes, quality of life, local disease control, and survival. Methods We conducted a systematic review of randomized clinical trials evaluating PBI delivered by any technique versus WBI in early-stage breast cancer. Searches were performed in CENTRAL/CCTR, EMBASE, MEDLINE, CINAHL, ISRCTN, and ClinicalTrials.gov, following PRISMA 2020 guidelines. Risk of bias was assessed using the Cochrane RoB 2 tool. Trials with low risk of bias were further evaluated. The CONSORT 2010 statement was used to guide standardized reporting, without influencing study selection. Results Of 340 records identified, 55 were randomized trials. After applying eligibility criteria and excluding studies with high or unclear risk of bias, 15 low-risk trials were included. Overall, PBI demonstrated comparable oncologic outcomes to WBI, with reduced treatment-related burden and improved quality of life in selected patients. However, results varied by technique and fractionation schedule. Notably, the RAPID trial reported higher rates of acute and late skin toxicity and worse cosmetic outcomes with twice-daily 3D external beam PBI, highlighting the importance of technique optimization and appropriate patient selection. Conclusions PBI is a safe and effective alternative to WBI in carefully selected patients with early-stage breast cancer, offering meaningful reductions in toxicity and treatment burden without compromising disease control. Technique-specific considerations remain critical to maximizing both clinical and cosmetic outcomes.