Timing of postmastectomy radiation therapy in two-stage expander/implant-based breast reconstruction: a systematic review and meta-analysis for the 2022 Japanese breast cancer society clinical practice guideline

Background In immediate expander/implant reconstruction, postmastectomy radiation therapy (PMRT) can be administered at two different time points: during tissue expander insertion or after exchange with an implant. The optimal timing for PMRT remains unclear. We conducted a systematic review and meta-analysis to evaluate the impact of PMRT timing on the outcomes of patients with breast cancer undergoing two-stage expander/implant breast reconstruction. Methods A literature review of articles in English and Japanese up to March 2021 was performed using PubMed/MEDLINE, the Cochrane Library, and Ichushi-Web. Studies comparing the timing of PMRT in patients with breast cancer undergoing immediate two-stage expander/implant breast reconstructions and PMRT were included. The assessed outcomes included major complications, reconstruction failure, cosmesis, capsular contractures, and local recurrence. Results Eleven studies encompassing 1,628 cases were identified. These included one prospective cohort study, one prospective case–control study, and nine retrospective cohort studies. No significant differences were observed in major complications between PMRT to expander and PMRT to implant (odds ratio [OR] 1.11, 95% confidence intervals [CI] 0.72–1.73, P = 0.64). Reconstruction failure was more prevalent in the expander group (OR 2.33, 95% CI 1.43–3.82, P = 0.0007), while severe capsular contractures occurred less frequently in the expander group (OR 0.33, 95% CI 0.12–0.92, P = 0.03). Conclusions PMRT to expander was associated with higher reconstruction failure and lower severe capsular contracture rates, with no significant differences in major complications by timing. There is insufficient evidence to favor one approach over the other.