Development and Validation of Nomograms Predictive of Overall and Progression-Free Survival in Patients With Oropharyngeal Cancer

Abstract

<div class="section"> <a class="named-anchor" id="d4013634e261"> <!-- named anchor --> </a> <h5 class="section-title" id="d4013634e262">Purpose</h5> <p id="d4013634e264">Treatment of oropharyngeal squamous cell carcinoma (OPSCC) is evolving toward risk-based modification of therapeutic intensity, which requires patient-specific estimates of overall survival (OS) and progression-free survival (PFS). </p> </div><div class="section"> <a class="named-anchor" id="d4013634e266"> <!-- named anchor --> </a> <h5 class="section-title" id="d4013634e267">Methods</h5> <p id="d4013634e269">To develop and validate nomograms for OS and PFS, we used a derivation cohort of 493 patients with OPSCC with known p16 tumor status (surrogate of human papillomavirus) and cigarette smoking history (pack-years) randomly assigned to clinical trials using platinum-based chemoradiotherapy (NRG Oncology Radiation Therapy Oncology Group [RTOG] 0129 and 0522). Nomograms were created from Cox models and internally validated by use of bootstrap and cross-validation. Model discrimination was measured by calibration plots and the concordance index. Nomograms were externally validated in a cohort of 153 patients with OPSCC randomly assigned to a third trial, NRG Oncology RTOG 9003. </p> </div><div class="section"> <a class="named-anchor" id="d4013634e271"> <!-- named anchor --> </a> <h5 class="section-title" id="d4013634e272">Results</h5> <p id="d4013634e274">Both models included age, Zubrod performance status, pack-years, education, p16 status, and T and N stage; the OS model also included anemia and age × pack-years interaction; and the PFS model also included marital status, weight loss, and p16 × Zubrod interaction. Predictions correlated well with observed 2-year and 5-year outcomes. The uncorrected concordance index was 0.76 (95% CI, 0.72 to 0.80) for OS and 0.70 (95% CI, 0.66 to 0.74) for PFS, and bias-corrected indices were similar. In the validation set, OS and PFS models were well calibrated, and OS and PFS were significantly different across tertiles of nomogram scores (log-rank <i>P</i> = .003;&lt; .001). </p> </div><div class="section"> <a class="named-anchor" id="d4013634e279"> <!-- named anchor --> </a> <h5 class="section-title" id="d4013634e280">Conclusion</h5> <p id="d4013634e282">The validated nomograms provided useful prediction of OS and PFS for patients with OPSCC treated with primary radiation-based therapy. </p> </div>