Evaluation of the Prognostic Significance of Altered Mammalian Target of Rapamycin Pathway Biomarkers in Upper Tract Urothelial Carcinoma

Objective To evaluate the prognostic value of altered mammalian target of rapamycin (mTOR) pathway biomarkers in upper tract urothelial carcinoma (UTUC). Materials and Methods We performed a multi-institutional review of clinical and pathologic information on patients receiving extirpative surgery for UTUC from 1990 to 2008. Immunohistochemistry for phosphorylated-S6, mTOR, phosphorylated-mTOR, PI3K, phosphorylated-4EBP1, phosphorylated-AKT, PTEN, HIF-1a, raptor, and cyclin D was performed on tissue microarrays from radical nephroureterectomy (RNU) specimens. Prognostic markers were identified and the significance of altered markers was assessed with the Kaplan-Meier analysis and the Cox regression analysis. Results Six hundred twenty patients were included. Over a median follow-up of 27.3 months, 24.6% of patients recurred and 21.8% died of UTUC. On multivariate analysis, PI3K (odds ratio, 1.28; P =.001) and cyclin D (odds ratio, 3.45; P =.05) were significant predictors of clinical outcomes. Cumulative marker score was defined as low risk (no altered markers or 1 altered marker) or high risk (cyclin D and PI3K altered). Patients with high-risk marker score had a significantly higher proportion of high-grade disease (91% vs 71%; P <.001), non-organ-confined disease (61% vs 33%; P <.001), and lymphovascular invasion (35% vs 20%; P =.001). The Kaplan-Meier analysis demonstrated a significant difference in cancer-specific mortality (CSM) based on the risk groups. On Cox regression multivariate analysis for CSM incorporating non-organ-confined disease, grade, lymphovascular invasion, tumor architecture, and marker score, high-risk biomarker score was an independent predictor of CSM (hazard ratio, 1.5; 95% confidence interval, 1.04-2.3; P =.03). Conclusion Alterations in mTOR pathway correlate with established adverse pathologic features and independently predict inferior oncologic outcomes. Incorporation of mTOR-based marker profiles may allow for enhanced patient counseling, risk stratification, and individualized treatment regimens.