INTRODUCTIONCurrent recommendations preconize prophylactic mastectomy for women over 30 with increased risk of breast cancer. Several surgical techniques are available to perform bilateral mastectomy with or without breast reconstruction. Our primary objective was to evaluate the feasibility of the Endoscopic Nipple Sparing Mastectomy (E-NSM) technique, without robotic assistance, using a single axillary incision and with immediate reconstruction using a prepectoral prosthesis in prophylactic indications. The secondary objectives were to evaluate the risks of postoperative complications and the esthetic results.MATERIAL AND METHODSThis is a preliminary report of a prospective single-center interventional clinical study with a final enrolment target of 20 patients. The primary endpoint was the rate of complete surgical procedures per E-NSM. The secondary endpoints were the rate of conversions to conventional surgery, infections, hematomas, skin injury, pain and esthetic results (Breast-Q questionnaire, additional cosmetic procedures).RESULTSFrom April 2019 to June 2022, 10 patients were included for 19 procedures (9 bilateral mastectomies, 1 unilateral). All surgical procedures were complete; no conversion to conventional surgery was required. The rate of complications per procedure requiring revision surgery was 16% (1 skin necrosis, 1 postoperative hematoma and 1 surgical site infection). No prosthesis was removed. The seroma rate was 5%. All patients would recommend this technique and were very satisfied or satisfied with the esthetic result. A second cosmetic procedure (lipofilling) was necessary in 50% of patients.DISCUSSIONThese preliminary data attest to the feasibility and safety of the E-NSM approach, and should be confirmed on a larger cohort and longer-term follow-up.CLINICALTRIALSGOV IDENTIFIERNCT03838549.