Molecular subtype and risk of local recurrence after nipple‑sparing mastectomy for breast cancer

The present study aimed to investigate whether local recurrence (LR) after nipple-sparing mastectomy (NSM) and reconstruction was associated with i) Ki67 values and molecular subtypes of the initial lesions, and ii) the size of the initial tumor and the size of the implant. A total of 156 patients with breast cancer with a mean age of 51.58 years (age range, 26-75 years) who underwent NSM with primary implant breast reconstruction were analyzed. After surgery, the mean follow-up time was 59.26 months (range, 17-85 months). Molecular subtypes, Ki67 values, estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status were recorded for each patient. Additionally, information regarding the size of the implant and the initial tumor size were collected. The information was used to assess LR. For univariate analyses of risk factors, χ² test, Fisher's exact test, Mann-Whitney U test and Student's t-test for independent samples were used. For multivariate analyses, a Cox proportional-hazards model was used. NSM was the primary treatment for breast cancer in 34/156 patients (21.8%), while 122/156 (78.2%) of patients received neoadjuvant chemotherapy followed by surgery. Luminal B was the most frequent molecular subtype, detected in 82/156 patients (52.6%), whereas the luminal A subtype was detected in 37 patients (23.7%) and the HER2-enriched subtype was detected in 17/156 patients (10.9%). Ki67 expression was low in 13/156 patients (8.3%), while medium expression was detected in 78/156 patients (50.0%) and high expression was present in 58/156 patients (37.2%). LR was noted in 17/156 patients (10.9%). As determined by univariate analysis, lower ER (P=0.010) and PR (P=0.008) expression were indicated to be significant risk factors for LR. In conclusion, in the present patient cohort, low ER and PR expression were risk factors for LR of breast cancer, whereas Ki67 status and molecular subtype were not statistically significant risk factors for LR. Additionally, the size of the initial tumor and the size of the implant were not risk factors for LR. These findings are consistent with the current literature, and should be utilized when discussing treatment options and potential clinical outcomes with patients prior to surgical management.