Prognostic Importance of PTEN and P53 in Aggressive Luminal A Subtype Breast Cancers

While prognostic and predictive factors in breast cancer are well established, data on aggressive behavior in luminal A subtype breast cancers are limited. The aim of this study was to investigate histomorphological and clinicopathological parameters that may predict treatment resistance and aggressive behavior in luminal A subtype, as well as the expression of two key proteins, PTEN and p53, involved in breast carcinoma development.

We included breast carcinoma cases diagnosed at a Turkish University Hospital between 2016 and 2017. Tumor tissue with internal control was available for all cases. PTEN and p53 expression were evaluated immunohistochemically, based on staining strength and percentage.

Of the 114 cases diagnosed in the study period, 18 (%) were recurrent and 5 (%) were Luminal A subtype. We observed significantly lower overall and disease-free survival in patients with ≤50% tumor infiltrating lymphocytes density, which was present in all recurrent cases. PTEN immunoreactivity scores were <6 in all recurrent luminal A cases, but no significant difference was found between recurrent and non-recurrent cases (p>0.05). The p53 H-score for luminal A was significantly lower than in luminal B, triple negative, and human epidermal growth factor receptor 2+ groups (p<0.05). Furthermore, p53 H-scores <50 were more common in grade 2 tumors than in grade 3 (p<0.05).

PTEN loss, observed in all recurrent luminal A cases and 77.1% of all cases, supports its role as a tumor suppressor. The findings suggest that PTEN expression loss may be a prognostic marker, and immune-modulating treatments should be considered for breast cancer patients.