Immediate 2-Stage breast reconstruction outcomes after proton or photon postmastectomy radiotherapy

To evaluate the impact of postmastectomy radiotherapy (PMRT) on immediate breast reconstruction (IBR) outcomes among patients treated with proton or photon radiotherapy.

Patients who had undergone mastectomy, immediate breast reconstruction, and PMRT at our institution were included in a retrospective analysis of risk factors for surgical site infection (SSI), unplanned reoperation, and reconstruction failure. Univariate Cox models were used to examine associations of variables with reconstruction outcomes.

Two-hundred thirty-one women were included, of whom 224 (97.0 %) underwent two-stage IBR with placement of a tissue expander and 7 (3 %) had direct-to-implant IBR. One-hundred sixty-five patients (71.4 %) received proton and 65 (28.6 %) received photon therapy. Twenty-nine patients (12.6 %) received hypofractionation. Median follow-up was 1.8 years. Two-year cumulative risk of SSI was 17.83 % (95 % CI 12.27-24.41 %); unplanned reoperation was 16.19 % (95 % CI 10.06-22.10 %); and reconstruction failure was 7.60 % (95 % CI 3.55-12.11). On multivariable analysis, prophylactic use of Mepitel Film reduced the risk of SSI [HR: 0.35 (95 % CI: 0.18-0.69), p = 0.002] and unplanned reoperation [HR: 0.39 (95 % CI: 0.20-0.79), p = 0.008]. The small number of events (n = 16) precluded multivariable analysis of reconstruction failure; on univariate analysis, receipt of a chest wall boost [HR: 4.98 (95 % CI: 1.12-22.10), p = 0.035] and/or lymph node boost [HR: 3.66 (95 % CI: 1.25-10.73), p = 0.018] were associated with reconstruction failure.

Although approximately one-fifth of women experienced SSI or unplanned reoperation, the rate of reconstruction failure was low (7.6%) and most women achieved a successful reconstruction outcome with PMRT using photons or protons. The lower rate of SSI and unplanned reoperation with use of Mepitel Film highlights the need for further evaluation.