Background: Although rates of total skin-sparing (nipple-sparing) mastectomies are increasing, the oncologic safety of this procedure has not been evaluated in invasive lobular carcinoma (ILC). ILC is the second most common type of breast cancer, and its diffuse growth pattern and high positive margin rates potentially increase the risk of poor outcomes from less extensive surgical resection.
Methods: We compared time to local recurrence and positive margin rates in a cohort of 300 patients with ILC undergoing either total skin-sparing mastectomy (TSSM), skin-sparing mastectomy, or simple mastectomy between the years 2000-2020. Data were obtained from a prospectively maintained institutional database and were analyzed by using univariate statistics, the log-rank test, and multivariate Cox proportional hazards models.
Results: Of 300 cases, mastectomy type was TSSM in 119 (39.7%), skin-sparing mastectomy in 52 (17.3%), and simple mastectomy in 129 (43%). The rate of TSSM increased significantly with time (p < 0.001) and was associated with younger age at diagnosis (p = 0.0007). There was no difference in time to local recurrence on univariate and multivariate analysis, nor difference in positive margin rates by mastectomy type. Factors significantly associated with shorter local recurrence-free survival were higher tumor stage and tumor grade.
Conclusions: TSSM can be safely offered to patients with ILC, despite the diffuse growth pattern seen in this tumor type.