Localisation of phosphorylated mTOR expression is critical to tumour progression and outcomes in patients with endometrial cancer

Correlations between mammalian target of rapamycin (mTOR) expression, and clinicopathological features, outcome and Akt expression in endometrial endometrioid adenocarcinoma (EEC) were investigated. Tumour samples were obtained from 82 patients with EEC who had undergone hysterectomy, and phosphorylated mTOR (p-mTOR) and Akt (p-Akt) expression in the cytoplasm and nucleus was analysed by immunohistochemical staining. Nuclear p-mTOR was significantly elevated in poorly differentiated tumours and positively correlated with lymph node involvement (P = 0.05). Nuclear p-mTOR expression was associated with significantly shorter relapse-free survival (RFS) (P < 0.01) and slightly shorter overall survival (OS) (P = 0.08). Cytoplasmic expression of p-mTOR was not correlated with any clinicopathological factors. Although not significant, cytoplasmic p-mTOR expression was associated with shorter PFS and OS (P = 0.09, P = 0.283, respectively). Neither cytoplasmic nor nuclear p-Akt expression was associated with clinicopathological factors or with survival. Localisation of p-mTOR may be critical for tumour progression and outcomes in patients with EEC.