Surgical Management of Ipsilateral Breast Cancer Recurrence After Conservative Mastectomy and Prepectoral Breast Reconstruction: Exploring the Role of Wide Local Excision

<b>Background:</b> Conservative mastectomy with prepectoral breast reconstruction is becoming increasingly widespread and validated in recent years. Today, while aesthetic advantages and improvement in quality-of-life outcomes are widely acknowledged, oncological safety remains subject of debate. There is limited evidence on residual breast tissue after conservative mastectomy, and it still represents an unknown risk for local recurrence. The recent spread of this surgical technique precludes a standardized surgical approach in case of local recurrence of ipsilateral breast cancer, and the lack of evidence in the literature complicates the decision-making process. The objective of this study is to describe the surgical treatment of local relapses for breast cancer patients following conservative mastectomy and prepectoral implant-based reconstruction. <b>Methods:</b> Between January 2018 and May 2024 at a single institution, 648 consecutive patients underwent conservative mastectomy and prepectoral reconstruction as their primary treatment. We identified 12 patients with T1-2 breast cancer who subsequently had histologically confirmed ipsilateral breast cancer recurrence and a local wide excision or radical mastectomy were performed. Each clinical case was discussed in a multidisciplinary meeting to define the most appropriate surgical treatment. At time of diagnosis of recurrence, patients with lymph node metastasis or systemic involvement were excluded from the study. <b>Results:</b> Among 648 consecutive patients who underwent conservative mastectomy, 12 with histologically confirmed ipsilateral breast cancer recurrence were included. The mean interval to recurrence was 43 months (range 10-76 months) from the primary operation. Recurrence sites were as follows: upper outer quadrant in four patients (33.4%), upper inner quadrant in three (25.0%), lower inner quadrant in two (16.6%), lower outer quadrant in one (8.4%), and central quadrant with nipple involvement in two (16.6%). Of the 12 patients, 9 (75%) underwent wide local excision, including 2 who also received partial capsulectomy, while 3 (25%) required radical mastectomy with implant removal. Adjuvant radiation therapy was administered to 6 patients (50%)-5/6 (83.3%) in the excision group and 1/6 (16.7%) in the mastectomy group. No significant differences were observed in distant disease-free survival or overall survival between the two groups. <b>Conclusions:</b> Currently, surgical treatment of ipsilateral breast tumor recurrence following conservative mastectomy and prepectoral breast reconstruction is not reported in the literature, and this study represents the first instance where wide local excision is described. The management of ipsilateral recurrence should be discussed in multidisciplinary meetings and could be performed safely in selected cases, sparing the prosthesis and avoiding radical mastectomy.