Wilson TG, et al. - In human papilloma virus (HPV) positive and negative head and neck cancer (HNSCC) patients treated by chemoradiation, researchers explored the connection between the mechanistic target of rapamycin (MTOR) and clinical outcome. A tissue microarray (TMA) consisting of cores from 109 HNSCC patients treated with definitive chemoradiation was built and stained with p16 and MTOR antibodies and expression correlated with clinicopathological characteristics and clinical outcome. According to results, MTOR varied widely between tumor cores and was not correlated with HPV status or clinicopathological characteristics. A positive relationship was found with pretreatment FDG uptake. MTOR predicted for shorter locoregional control, diseases free survival, and overall survival in HPV negative patients. Findings suggested no association of MTOR expression with outcome in HPV positive patients. MTOR's prognostic significance depends on HPV status.