Postmastectomy Radiation Therapy in the Setting of Two-Stage Retropectoral Implant-Based Breast Reconstruction: Should It be Delivered Before or After Implant Exchange? A Retrospective Analysis on 183 Patients.

[INTRODUCTION] Postmastectomy radiation therapy (PMRT) has a primary role in the treatment of locally advanced breast cancer; however, the most appropriate timing of irradiation in immediate tissue expander breast reconstruction (ITEBR) still remains unknown.

[METHODS] A retrospective review was performed on all women undergoing mastectomy and retropectoral ITEBR at Campus Bio-Medico University Hospital in Rome, Italy, between 2010 and 2019. The patients were categorized into three cohorts: patients undergoing PMRT with the tissue expander (TE) in situ, patients with PMRT delivered to the permanent implant (PI), patients who were not administered RT. Complications and failure rates were analysed and compared. Potential predictors of adverse outcomes were analysed.

[RESULTS] Over 10 years, 183 patients underwent retropectoral ITEBR (55 PMRT-TE, 50 PMRT-PI, 78 no-PMRT). The three groups were well matched with respect to patient- and treatment-related factors (p > 0.05), with the exception of neoadjuvant chemotherapy and irradiation. The mean follow-up was, respectively, 4.58, 7 and 5.75 years. Radiotherapy either to the TE or to the PI was independently associated with failure and conversion to autologous procedures (p < 0.0001). Failure rate was significantly higher when TE was irradiated (p = 0.03). PMRT was associated with severe capsular contracture development (p < 0.00001), the odds being higher when irradiation was delivered after implant exchange (p = 0.04). Increased BMI was significantly associated with failure.

[CONCLUSIONS] When PMRT is delivered to the TE, the risk of failure is higher (OR 2.77); when the PI is irradiated, reconstruction will more likely be affected by severe capsular contracture (OR 2.7). However, considering that the overall risk of severe capsular contracture correlated to PMRT is higher than failure, we believe that irradiation should be delivered to the TE. Performing a proper capsuloplasty at the time of implant exchange, indeed, allows to correct the deformities related to radiation-induced capsular contracture. Patients with unfavourable outcomes after TE placement and RT, instead, can be directly switched to autologous reconstruction.

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