Fas expression in primary breast cancer is related to neoplastic infiltration of perilymphatic fat

Purpose: Various studies have revealed that both Fas and its ligand play an important role in cancer biology. The aim of our study was to determine if there is a relationship between the expression of Fas or Fas-ligand in breast cancer and the presence of malignant cells in perilymphatic fat. Material/Methods: Tumor samples from 147 consecutive breast cancer patients, aged 35-81 (median, 59), were subjected to analysis. The expressions of Fas and Fas-ligand were determined immunohistochemically. Results: The expression of Fas, but not Fas-ligand, was significantly less frequent in breast cancer patients in whom malignant cells infiltrated through the perilymphatic fat (p=0.042). The infiltration of paranodal fatty tissue occurred more often in cases of ductal carcinomas (p=0.008), larger primary tumors (pT≥2, p=0.030) and regional lymph node involvement (pN≥1, p=0.021). Univariate analysis revealed that perilymphatic fat infiltration shortened overall survivals in breast cancer patients (p=0.05), similarly to postmenopausal status (p=0.034), age >60 years (p=0.05) and regional lymph node involvement (p=0.05). None of the aforementioned factors, however, was revealed as an independent predictor of survival in multivariate analysis. Conclusions: The study showed that lack of Fas in primary breast cancer is associated with perilymphatic fat infiltration. Consequently, both the absence of Fas in the primary tumor and the occurrence of neoplatic cells in paranodal fatty tissue should be considered in the prognosis, complementing existing conventional factors.