Postmastectomy radiation therapy for implant-based breast reconstruction: a systematic review and meta-analysis for the 2022 Japanese Breast Cancer Society Clinical Practice Guideline.

[BACKGROUND] Implant-based breast reconstruction is the most commonly performed reconstructive technique following mastectomy. With an increasing number of patients undergoing implant-based breast reconstruction, concerns have arisen regarding the safety of postmastectomy radiation therapy (PMRT) in reconstructed breasts. This study aimed to investigate the safety of PMRT in implant-based breast reconstruction.

[METHODS] A comprehensive literature search was conducted for articles published up to March 2021. Eligible studies included clinical trials and observational studies comparing outcomes between patients with breast cancer undergoing immediate implant-based breast reconstruction with PMRT and those without PMRT. The primary outcomes included major complications, reconstruction failure, capsular contracture, and cosmetic outcomes. Pooled odds ratio (OR) with 95% confidence interval (CI) were calculated using a random-effects model.

[RESULTS] A total of 23 studies were identified, comprising one case-control study, one prospective cohort study, and 21 retrospective cohort studies. PMRT was significantly associated with increased rates of major complications (OR 2.62, 95% CI 1.82-3.77, P < 0.00001), reconstruction failure (OR 2.53, 95% CI 2.00-3.20, P < 0.00001), and capsular contracture (OR 9.63, 95% CI 5.77-16.06, P < 0.00001). Furthermore, cosmetic outcomes were significantly poorer in patients undergoing PMRT compared with those not receiving PMRT (OR 3.55, 95% CI 1.80-6.98, P < 0.003).

[CONCLUSIONS] This meta-analysis demonstrated that PMRT in implant-based breast reconstruction is associated with a significantly increased risk of adverse outcomes. Given these risks, treatment decisions should involve through discussions with patients to ensure that they are fully informed of the potential benefits and complications.