Abstract P2-14-09: A novel nipple aleolar complex involvement predictive index (NACPI) for indicating nipple sparing mastectomy in breast cancer patients
Authors: Seki H , Sakurai T , Shimizu K , Mizuno S , Tokuda T , Kaburagi T , Seki M , Karahashi T , Nakajima K 
Published: May 2019

Background: While Preservation of NAC is concerned to increase the risk of local recurrences in the retroareolar glandular tissue, nipple sparing mastectomy (NSM) is increasing in patients with breast cancer and has been shown to result in better cosmetic outcome and the benefit for quality-of-life. It is necessary to predict accurately NAC involvement in order to select which patients may be candidates to NSM. The distance from the nipple to the tumor (DNT) is proposed as one of the best criteria to select the patient. The purpose of this study is to identify the predictors of NAC involvement retrospectively and to develop a clinical predictive model to select the patients who can be offered preservation of NAC.Methods: A total of 168 patients with primary operable breast cancer who received subcutaneous mastectomy for breast reconstruction at Saitama Medical Center during July 2013 to December 2017 were selected from the hospital's surgical database. NAC involvement was defined by the presence of invasive carcinoma and/or ductal carcinoma in situ at the subareolar margin.

Results: Of the 148 patients who were preserved NAC, 89.9% (133/148) were NAC involvement negative and 10.1% (15/148) were positive in permanent pathological specimens. Of the 20 patients who were resected NAC, NAC involvement positivity was only 50.0% (10/20). This revealed that NAC involvement with a sensitivity (SN) of 40.0%, a specificity (SP) of 93.0%, a positive predictive value (PPV) of 50.0% and a negative predictive value (NPV) of 89.9% (AUC=0.665, 95%CI: 0.5345-0.796). In 140 patients who were performed intraoperative sub-nipple frozen section biopsy, the findings was significantly associated with NAC involvement (P&lt;0.001), and which predict the NAC involvement with a SN of 93.3%, a SP of 89.6%, a PPV of 51.9%, and a NPV of 99.1% (AUC=0.915, 95%CI: 0.835-0.994). In the concordance rate between frozen section findings and definitive pathologic results, DCIS was 53% (9/17), atypical cell was 50% (2/4) and invasive ductal carcinoma was 100% (3/3). Correlation between NAC involvement and clinicopathological factors, tumor size ≥4cm (P&lt;0.001), DNT &lt;1cm by MMG (P=0.002), DNT &lt;1cm by MRI (P&lt;0.001), nipple contrast findings by MRI (P&lt;0.001), tumor in central portion (P&lt;0.001), multicentirc/focal lesion (P&lt;0.001), c(N) positive (P=0.014) were significant relation with NAC involvement. Each predictors were scored 0 or 1, and the total score of 0-3 points was defined as low risk, 4 points as intermediate risk, and 5-7 points as high risk. Depending on this categorized classification, the NAC involvement rate was 3.5% (5/142) in low risk, 68.7% (11/16) in intermediate risk, 90.0% (9/10) in high risk and there was a significant correlation between the risk group and NAC involvement (P &lt;0.001). Notably, assuming that NAC is preserved for low risk patients and is resected for intermediate and high risk patients, NACPI contributes to improve the accuracy of selecting the surgical procedures (SN 80.0%, SP 95.8%, PPV 76.9%, NPV 96.5% (AUC=0.879, 95%CI: 0.784-0.974)).Conclusion: This study suggests that NACPI can help us indicating subcutaneous mastectomy for the breast cancer patients who request preserve NAC with more oncological safety.

Citation Format: Seki H, Sakurai T, Shimizu K, Mizuno S, Tokuda T, Kaburagi T, Seki M, Karahashi T, Nakajima K. A novel nipple aleolar complex involvement predictive index (NACPI) for indicating nipple sparing mastectomy in breast cancer patients [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-09.