Magnetic Resonance Imaging and Clinicopathological Factors for the Detection of Occult Nipple Involvement in Breast Cancer Patients

PURPOSE Nipple sparing mastectomy provides good cosmetic results and low local recurrence rates for breast cancer patients. However, there is a potential risk of leaving an occult tumor within the nipple, which could lead to cancer relapse and poor prognosis for the patient. The objective of this study was to investigate the occult nipple involvement rate in mastectomy specimens, and to identify preoperative magnetic resonance imaging (MRI) findings and the clinicopathological characteristics of the primary tumor that may correlate with nipple invasion. METHODS Four hundred sixty-six consecutive mastectomy samples with grossly unremarkable nipples were evaluated. Demographic and clinicopathological data were collected. Nipple involvement was evaluated using serial histological sections. The tumor size and tumor-nipple distance were measured using preoperative MRI images. RESULTS Thirty-six of the 466 therapeutic mastectomy specimens (7.7%) were found to have occult nipple involvement. In univariate analysis, tumor size, tumor-nipple distance, lymph node status, p53 mutation, and lymphovascular invasion (LVI) were found to influence the likelihood of nipple involvement. Multivariate logistic regression analysis, adjusted by lymph node status, p53 mutation, and LVI, showed that tumor size and tumor-nipple distance were predictive factors indicating nipple involvement. With regard to tumor location, only tumors in the central area of the breast showed a significant association with nipple involvement. CONCLUSION In this study, a statistically significant association was found between occult nipple involvement and tumor size, tumor-nipple distance, axillary lymph node status, LVI, and p53 mutation. A cutoff point of 2.2 cm for tumor size and 2 cm for tumor-nipple distance could be used as parameters to predict occult nipple involvement.