Abstract Indications for nipple sparing mastectomy Jean-Yves Petit (EIO - Milan) Benefit of the nipple areola complex (NAC) conservation has been shown (1,). To reduce the risk of local recurrences (LR), inclusion criteria and/or add localized radiation therapy have been proposed. The LR rate in patients receiving NSM is comparable with the rate in modified radical or skin-sparing mastectomies(2) Same conclusions have been raised in a study of one thousand NSM in Milan(3). LR were observed in 3 to 6% of patients at 5 years, consistent with traditional mastectomy. Today, the quality of the surgery allows for a more radical glandular removal in the retro areolar area. The significant risk factors associated with LR for the group of invasive carcinomas were grade, over expression/amplification of HER2/neu and breast cancer molecular subtype Luminal B. In the group of intra epithelial neoplasia the risk factors were age ( < 45 years), absence of estrogen receptors, grade, HER2/neu overexpression and high Ki-67(4). The quality of the duct resection in the nipple questions the role of the intra operative radiotherapy. J. Rusby demonstrated that although several ducts were originating from the base of the areola, most of them are concentrated in the axis of the nipple and concluded that a subtotal removal of the duct can be performed(5). We decided at the IEO to postpone the radiotherapy on the NAC to the cases with non radical cancer resection . Tips and trick will be shown to improve the quality of the NSM and the quality of the breast reconstruction. Indication of implant versus autologous flap reconstruction will be discussed as well as the use of ADM. The risk and the type of complications and specially nipple areola necrosis will be evaluated. References : 1-Does nipple preservation in mastectomy improve satisfaction with cosmetic results, psycho-logical adjustment, body image and sexuality? Didier F, Radice D, Gandini S, Bedolis R, Rotmensz N, Maldifassi A, Santillo B, Luini A, Galimberti V, Scaffidi E, Lupo F, Martella S, Petit JY. Breast Cancer Res Treat. 2009 Dec;118(3):623-33 2-Comparison of oncological safety between nipple sparing mastectomy and total mastectomy using propensity score matching. Seki T, Jinno H, Okabayashi K, Murata T, Matsumoto A, Takahashi M, Hayashida T, Kitagawa Y. Ann R Coll Surg Engl. 2015 May;97(4):291-7. 3-Risk factors associated with recurrence after nipple-sparing mastectomy for invasive and intraepithelial neoplasia. Petit JY, Veronesi U, Orecchia R, Curigliano G, Rey PC, Botteri E, Rotmensz N, Lohsiriwat V, Cassilha Kneubil M, Rietjens M. Ann Oncol. 2012 Aug;23(8):2053-8. 4-Nipple sparing mastectomy with nipple areola intraoperative radiotherapy: one thousand and one cases of a five years experience at the European institute of oncology of Milan (EIO). Petit JY, Veronesi U, Orecchia R, Rey P, Martella S, Didier F, Viale G, Veronesi P, Luini A, Galimberti V, Bedolis R, Rietjens M, Garusi C, De Lorenzi F, Bosco R, Manconi A, Ivaldi GB, Youssef O. Breast Cancer Res Treat. 2009 Sep;117(2):333-8. 5-Breast duct anatomy in the human nipple: three-dimensional patterns and clinical implica-tions. Rusby JE, Brachtel EF, Michaelson JS, Koerner FC, Smith BL. Breast Cancer Res Treat. 2007 Dec;106(2):171-9. Citation Format: Petit J-Y. Indications for nipple sparing mastectomy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr ES3-2.