Impact of immediate breast reconstruction on perioperative therapy: insights from a Japanese Nationwide Registry.

Background: Immediate breast reconstruction (IBR) is a common oncoplastic procedure used in breast cancer surgery. This study aims to investigate compliance with prosthetic breast reconstruction guidelines and its impact on perioperative treatment.

Methods: We reviewed data from the National Clinical Database-Breast Cancer Registry between January 2019 and December 2020. We compared perioperative treatment implementation between the IBR and non-IBR groups by subtype matching for age, menopausal status, T stage, N stage, and histology.

Results: A total of 8,860 patients with breast cancer who underwent IBR (6,075 breast prostheses, 2,492 autologous tissues, and 293 others) were identified. The compliance rate with the guidelines for prosthetic breast reconstruction was 97.7%. After matching, chemotherapy for luminal A-like diseases was significantly less frequent in the IBR group than in the non-IBR group (16.3% vs 20.5%, p < 0.001), and radiotherapy was less frequent in luminal A-like and HER2-positive patients (7.2% vs 9.0%, p = 0.010 and 7.1% vs 11.4%, p = 0.005, respectively). Among the 1-3 node-positive cases, fewer patients with prosthetic IBR received radiotherapy than those without IBR (15.7% vs 26.4%, p < 0.001).

Conclusion: Prosthetic breast reconstruction was performed with strict adherence to the Japanese guidelines. The implementation rates of chemotherapy and radiotherapy were lower in the specific IBR group than those in the non-IBR group. Therefore, large-scale, long-term follow-up data are required.