Addition of the tumour-stroma ratio to the 8th edition American Joint Committee on Cancer staging system improves survival prediction for patients with oral tongue squamous cell carcinoma

Aims One of the objectives of current research is to customise the treatment of cancer patients. The achievement of this objective requires stratification of patients based on the most significant prognostic factors. The aims of this study were to evaluate the prognostic value of the tumour-stroma ratio (TSR), defined as the proportion of tumour cells relative to surrounding stroma, in patients with oral tongue squamous cell carcinoma (OTSCC), and to develop a prognostic nomogram based on the most significant clinicopathological features. Methods and results Clinicopathological data of 211 patients treated at 'Ospedali Riuniti' General Hospital (Ancona, Italy) for OTSCC were collected. One hundred and thirty-nine patients were restaged according to the 8th edition American Joint Committee on Cancer (AJCC) staging system. Evaluation of the TSR was performed on haematoxylin and eosin-stained slides, and correlation with survival outcomes was evaluated. In addition, with the aim of integrating the independent value of the TSR with the 8th edition AJCC staging system, a prognostic nomogram for OTSCC has been developed. OTSCC with a low TSR (i.e. a high proportion of stroma and a low proportion of tumour cells) was shown to have negative prognostic value in terms of disease-specific survival, with a hazard ratio (HR) of 1.883 and a 95% confidence interval (CI) of 1.033-3.432 (P = 0.039), and overall survival (HR = 1.747, 95% CI 0.967-3.154;P = 0.044), independently of other histological and clinical parameters. For the cohort of 139 patients restaged according to the 8th edition AJCC staging system, variables correlating with a poor prognosis were: the TSR, perineural invasion, and sex. The nomogram built on these parameters showed good predictive capacity, outperforming the 8th edition AJCC staging system in stratifying disease-specific survival in OTSCC patients. Conclusions Including the TSR in the predictive model could improve risk stratification of OTSCC patients and aid in making treatment decisions.