A Model Using Concomitant Markers for Predicting Outcome in Human Papillomavirus Positive Oropharyngeal Cancer

Objective: Head-neck cancer therapy has become intensified. With radiotherapy alone, 3-year disease-free survival (DFS) is 80% for HPV-positive TSCC/BOTSCC and better for patients with favorable characteristics, suggesting therapy could be tapered for some, decreasing side-effects. Therefore, we built a model to predict progression-free survival for patients with HPV-positive TSCC and BOTSCC.

Material And Methods: TSCC/BOTSCC patients treated curatively between 2000 and 2011, with HPV16 DNA/E7 mRNA positive tumors examined for CD8 TILs, HPV16 mRNA and HLA class I expression were included. Patients were split randomly 65/35 into training and validation sets, and LASSO regression was used to select a model in the training set, the performance of which was evaluated in the validation set.

Results: 258 patients with HPV DNA/E7 mRNA positive tumors could be included, 168 and 90 patients in the respective sets. No treatment improved prognosis compared to radiotherapy alone. CD8 TIL counts and young age were the strongest predictors of survival, followed by T-stage <3 and presence of HPV16 E2 mRNA. The model had an area under curve (AUC) of 76%. A model where the presence of three of four of these markers defined good prognosis captured 56% of non-relapsing patients with a positive predictive value of 98% in the validation set. Furthermore, the model identified 35% of our cohort that was overtreated and could safely have received de-escalated therapy.

Conclusion: CD8 TIL counts, age, T-stage and E2 expression could predict progression-free survival, identifying patients eligible for randomized trials with milder treatment, potentially reducing side effects without worsening prognosis.