Phosphorylated mTOR expression correlates with poor outcome in early-stage triple negative breast carcinomas.

The mammalian target of rapamycin (mTOR) plays an important role in cell growth, proliferation, and metabolism. Some studies have associated phosphorylated mTOR (p-mTOR) expression with worse outcome in breast cancers. However, the significance of p-mTOR expression specifically in triple negative breast carcinoma (TNBC) is unknown. In this study, p-mTOR expression was evaluated by immunohistochemistry in 172 TNBCs and the result was correlated with clinicopathologic variables and disease outcome. The majority of tumors (72.1%) were p-mTOR positive; p-mTOR expression did not correlate with age, tumor size, grade, lymph node status, or tumor stage. In patients at stage 1 and 2 disease, those with p-mTOR expression had significantly worse overall as well as recurrence-free survival compared to those without p-mTOR expression. p-mTOR expression appears to be an adverse prognostic indicator in early-stage TNBCs. The assessment of p-mTOR expression in these tumors may also help to stratify patients for future target therapy studies.