Study Design Prospective, single-center, observational, non-interventional study conducted in routine clinical practice. No investigational treatments or modifications to standard diagnostic, therapeutic, or follow-up procedures are planned. Consecutive eligible patients undergoing endoscopic nipple-sparing mastectomy (NSM) with immediate breast reconstruction will be prospectively enrolled.

Background and Rationale Nipple-sparing mastectomy with immediate reconstruction is an established treatment for selected patients with breast cancer and women undergoing prophylactic mastectomy because of hereditary risk. Preservation of the nipple-areola complex (NAC) improves cosmetic outcomes, body image, and patient satisfaction while maintaining oncological safety. Endoscopic NSM is a minimally invasive alternative that may reduce scarring, surgical trauma, and recovery time while improving aesthetic outcomes without compromising oncological radicality. However, evidence remains limited, particularly in Europe, regarding feasibility, perioperative safety, sensory recovery, quality of life, reconstructive outcomes, and long-term oncological results. This study aims to prospectively collect real-world data from a consecutive cohort treated at a specialized breast center.

Primary Objective To evaluate the feasibility and surgical safety of endoscopic NSM with immediate breast reconstruction in patients undergoing prophylactic or therapeutic mastectomy.

Secondary Objectives To evaluate NAC sensory recovery at 6 and 12 months; assess oncological safety through surgical radicality and follow-up; evaluate quality of life and patient satisfaction using validated questionnaires; describe disease-free survival (DFS), overall survival (OS), reconstructive and aesthetic outcomes; and assess postoperative hospital stay.

Primary Endpoints Overall incidence of early surgical complications; incidence of NAC necrosis, skin flap necrosis, infection, seroma, hematoma, hospital readmission, reoperation, and implant loss; recovery of NAC sensation at 6 and 12 months; and pathological assessment of retroareolar margin status.

Secondary Endpoints BREAST-Q scores; local, regional, and distant recurrence; DFS; OS; and reconstructive/aesthetic outcomes.

Study Population and Sample Size Thirty consecutive adult women undergoing prophylactic or therapeutic NSM with immediate implant-based reconstruction according to multidisciplinary evaluation.

Main Inclusion Criteria Female; age 18-75 years; indication for prophylactic or therapeutic NSM; breast volume suitable for endoscopic surgery; Regnault ptosis ≤ Grade II; eligibility for immediate implant-based reconstruction; WHO/ECOG performance status <3; written informed consent.

Main Exclusion Criteria Inflammatory breast cancer or skin involvement; previous breast cancer surgery or radiotherapy to the affected breast; BMI >35 kg/m²; active smoking; ASA Physical Status >2; pregnancy or breastfeeding; inability to provide informed consent; participation in incompatible interventional clinical trials.

Observed Procedure Endoscopic NSM through a lateral inframammary incision using a combined open/endoscopic dissection. Intraoperative retroareolar frozen section and axillary staging (sentinel lymph node biopsy or axillary dissection) will be performed when indicated. Immediate prepectoral implant-based reconstruction will follow.

Data Collection and Follow-up Clinical, surgical, pathological, perioperative, and follow-up data will be prospectively recorded in a dedicated electronic Case Report Form. Patient-reported outcomes will be assessed using the validated BREAST-Q Reconstruction Module. Assessments will be performed preoperatively, intraoperatively, at 30 and 60 days, 6 months, 12 months, and annually up to 5 years. BREAST-Q will be administered at 6 months, 12 months, and annually thereafter.

Study Duration Enrollment will continue until 30 patients have been recruited. Each participant will be followed for 5 years.

Statistical Analysis This descriptive exploratory study will summarize categorical variables as frequencies and percentages and continuous variables using appropriate descriptive statistics. Long-term oncological outcomes will be reported as observed events, with DFS and OS estimated using Kaplan-Meier analysis when appropriate.

Ethics The study is observational and does not alter routine clinical management. No additional significant risks beyond standard surgical care are anticipated. Written informed consent is mandatory. Personal data will be pseudonymized and processed in accordance with the General Data Protection Regulation (EU 2016/679) and applicable national legislation.

Expected Benefits and Risks The study will provide prospective evidence on the feasibility, safety, functional recovery, quality of life, reconstructive outcomes, and oncological effectiveness of endoscopic NSM.