This study will prospectively evaluate the surgical outcomes of robotic nipple sparing mastectomy (NSM) compared with endoscopic assisted NSM or conventional NSM in the management of breast cancer. One-third patients would received R-NSM, another one-third received C-NSM while the other one-third would receive E-NSM.

Nipple-sparing mastectomy (NSM), which preserved the nipple areolar complex (NAC) and skin flap during mastectomy, was increasingly performed in breast cancer patients due to better cosmetic outcome, higher patient satisfaction, and maintained oncologic safety.

Minimal invasive surgery had become the main stream of operations, and new surgical innovations of NSM, like endoscopic nipple sparing mastectomy (E-NSM) or robotic nipple sparing mastectomy (R-NSM), were emerging and applied in the surgical treatment of breast cancer.

E-NSM, which is performed through small axillary and/or peri-areolar incisions, was reported to be associated with small inconspicuous incision and good cosmetic outcome. Conventional E-NSM was performed with two separate incisions over axilla and peri-areolar regions. E-NSM with areolar incision, just like NSM with areolar related incision (NAC ischemia/necrosis rate: range 7%-81.8%), was associated with increased NAC ischemia/necrosis (reported ranged: 9.1-19%). New technique modifications of E-NSM were emerging focusing on single axillary incision NSM, which spare the peri-areolar incision and thereby decrease the compromise of bloody supply from mastectomy skin flap, was reported to have low NAC necrosis rate (0%).

However, the 2-dimensional endoscopic in-line camera produces an inconsistent optical window around the curvature of the breast skin flap, and the internal mobility was limited and the dissection angles were inadequate with traditional endoscopic rigid tips instruments through single access. Due to the limitations of endoscopy instruments and technique difficulty, neither conventional E-NSM nor single access E-NSM was widespread used in breast cancer

R-NSM, which introduce da Vinci surgical platform through a small extra-mammary axillary or lateral chest wound to perform NSM, had been applied in the surgical treatment of early breast cancer or risk reducing mastectomy. R-NSM, which incorporated 3-dimensional (3D) imaging system and flexibility of robotic arm and instruments, was reported to have the potential to overcome the technique difficulty of E-NSM.

The preliminary results of R-NSM from current reported series and ours were safe, and associated with good cosmetic outcome and high patients' satisfaction. However, evidence comparing R-NSM to conventional NSM (C-NSM) or E-NSM was lacking.

In this study, the authors aim to investigate and analyze the clinical and aesthetic outcomes as well as the cost effectiveness of R-NSM through a prospective cohort of patients undergoing R-NSM, E-NSM or C-NSM.

Inclusion Criteria:

• A. Indications and selection criteria for nipple sparing mastectomy (NSM) in general and conventional nipple sparing mastectomy (C-NSM)
• NSM will be offered to patients who are suitable for mastectomy but keen to conserve nipple areolar complex (NAC), with or without reconstruction. Patients must not have clinical or radiological involvement of the NAC. Patients with nipple involvement proven via intra-operative frozen section analysis will receive NAC excision and hence a skin-sparing mastectomy (SSM) performed instead.

B. Indications and selection criteria for robotic nipple sparing mastectomy (R-NSM) or endoscopic nipple sparing mastectomy (E-NSM)

• The general inclusion criteria or pre-requisite for nipple sparing mastectomy apply to R-NSM or E-NSM as well.
• In addition, R-NSM or E-NSM should only include early stage breast cancer (carcinoma in situ, stage I - IIIA), a tumor size less than 5 cm, no evidence of multiple lymph node metastasis, and no evidence of nipple, skin or chest wall invasion.

Exclusion Criteria:

• - Contraindications for R-NSM, C-NSM or E-NSM include those with apparent NAC involvement, inflammatory breast cancer, breast cancer with chest wall or skin invasion, locally advanced breast cancer, breast cancer with extensive axillary lymph node metastasis (stage III B or later), and patients with severe co-morbid conditions, such as heart disease, renal failure, liver dysfunction, and poor performance status as assessed by the primary physicians
• Relative contraindications include women with large (breast cup size larger than E or breast mastectomy weight >600gm) or ptotic breast as the aesthetic outcomes may be suboptimal.

prospective, non-randomized, non-masking, open label, 3 arms