2921 - Hypofractionated Radiotherapy Compared to Conventional Fractionation after Breast Cancer Surgery: A Systematic Review and Meta-Analysis

Purpose/Objective(s): This study compares the effects of hypofractionated radiotherapy (HFRT) and conventional fractionated radiotherapy (CFRT) on locoregional control and cutaneous toxicity following breast cancer surgery. The primary endpoint was locorregional recurrence (LR), defined as cancer recurrence in the ipsilateral breast, chest wall, or regional lymph nodes, excluding distant metastases. Secondary endpoints included acute and late skin and subcutaneous toxicities in both HFRT and CFRT groups.

Materials/Methods: This systematic review and meta-analysis, registered in the PROSPERO database, included 31,651 patients and adhered to PRISMA guidelines. Between January and December 2022, 864 clinical trials were identified across PubMed (219), Scopus (378), and Web of Science (267). After removing 22 duplicates and excluding 815 articles that did not meet eligibility criteria, 27 studies were included. The research question was guided by the PICO framework: P (breast cancer patients), I (hypofractionated radiotherapy), C (any comparator intervention), O (injury recurrence). Inclusion criteria consisted of patients aged 18 or older with breast cancer (stages Tis-T4cN0-N3M0) who underwent conservative surgery or mastectomy, received adjuvant or neoadjuvant chemotherapy, and were treated with HFRT or CFRT. Methodological quality was assessed based on randomization sequence generation, allocation concealment, and blinding. Outcomes were evaluated using odds ratio (OR) and 95% confidence interval (CI) for local recurrence, adverse events, and cosmetic outcomes. Skin and subcutaneous toxicities were assessed using the Radiation Therapy Oncology Group (RTOG) criteria.

Results: No significant differences were observed between HFRT and CFRT in locorregional recurrence (OR = 0.89, 95%CI = 0.76-1.05, p = 0.17) or in late skin and subcutaneous toxicities (OR = 1.04, 95%CI = 0.56-1.93, p = 0.91). However, patients treated with HFRT had a higher likelihood (OR = 0.34, 95%CI = 0.20-0.59, p<0.01) of experiencing acute skin reactions greater than grade 2 compared to those treated with CFRT. This represents a statistically significant 66% reduction in the risk of =G2 lesions.

Conclusion: Our results suggest that HFRT is not inferior to CFRT in terms of LR and late skin and subcutaneous effects. Additionally, HFRT reduces the risk of acute toxicity reactions compared to CFRT. Therefore, HFRT may be a viable treatment option for breast cancer patients’ post-surgery, except for inflammatory carcinoma, which requires further randomized trials for conclusive evidence.