Hypofractionated vs. Conventional Radiotherapy in Breast Cancer Patients Who Underwent Breast Reconstruction: Toxicity Analysis

Abstract

<h3>Purpose/Objective(s)</h3> The efficacy and safety of hypofractionated RT has been demonstrated, but little is known about how hypofractionated RT affects breast-related complications after breast reconstruction. This study investigated whether hypofractionated adjuvant radiotherapy (RT) increased breast-related complication(s) compared to conventional RT in reconstructed breast cancer patients. <h3>Materials/Methods</h3> We analyzed breast-related complications of the patients who underwent breast reconstruction following mastectomy or breast-conserving surgery (BCS) between 2009 and 2018 at two institutions. Of all, 349 patients received immediate breast reconstructions and 129 had delayed breast reconstructions. All patients were treated with adjuvant RT using conventional fractionation (1.8-2.0 Gy for 5-7 weeks) or hypofractionation (2.4-3.0 Gy for 4-6 weeks). In case of delayed reconstruction, all patients had received post-mastectomy RT (PMRT) before reconstructive surgery was performed. A major breast complication was defined as a breast-related toxic event requiring re-operation or re-hospitalization during the follow-up period after the end of RT. <h3>Results</h3> The median follow-up was 32.3 months (4.8–118.5 months) for patients of immediate reconstruction and 43.5 months (6.5-119.7 months) for those of delayed reconstruction. In patients underwent immediate reconstruction following mastectomy, there was no significant difference in the incidence of any (30.1% vs 14.2% at 1 year; <b>P</b> = 0.064) or major breast-related complications (11.2% vs 7.7% at 1 year; <b>P</b> = 0.420) between conventional and hypofractionated RT regimens. In patients who underwent BCS followed by immediate reconstruction, incidence of any breast complication showed no difference between two RT groups (23.5% vs 17.3% at 1 year; <b>P</b> = 0.301) and no major breast complication was reported as well. Hypofractionated RT did not increase major wound problem including infection and dehiscence compared to conventional RT (<b>P</b> = 0.948). The incidence of major contracture was significantly lower in hypofractionated RT in this group of patients (<b>P</b> = 0.033). In patients underwent delayed reconstruction followed by mastectomy, no significant difference was found in the incidence of any (33.7% vs 34.1% at 1 year; <b>P</b> = 0.570) and major breast complications (12.0% vs 20.1% at 1 year; <b>P</b> = 0.623) in conventional versus hypofractionated RT. The two fractionation regimens showed no significant difference in the incidence of major wound problem as well (<b>P</b> = 0.397). The longer interval (> 10 months) between PMRT and the delayed reconstruction (HR, 0.28; <i>P</i> = 0.011) and the less body mass index (< 23) (HR, 0.36; <i>P</i> = 0.016) significantly decreased major breast complications. <h3>Conclusion</h3> Hypofractionated RT did not increased the incidence of any or major breast-related complications compared to conventional fractionation in the breast cancer patients who underwent reconstruction.