Abstract 65 Purpose Incidence of head and neck cancer (HNC) is high in South America, and survival data are scarce in this region. The InterCHANGE study was established by clinical groups from across South America and the International Agency for Research on Cancer, with the primary aim to study the impact of human papillomavirus (HPV) infection and sociodemographic, clinic, and lifestyle factors on survival after this malignancy. The current study examined the main predictors of survival after HNC in South America and estimated overall and conditional survival probabilities. Methods Patients were recruited during 2010 to 2016 from seven centers in Argentina, Brazil, Colombia, and Uruguay. A questionnaire obtained information on age, stage, and body mass index at diagnosis; sex; education; race; and comprehensive smoking and alcohol history. Blood samples were collected for HPV16 E6 testing—a surrogate marker for HPV16 infection. The Kaplan-Meier method and Cox proportional hazards regression were used for statistical analyses. Results Of 1,314 patients, 348 had oropharynx cancer and 966 nonoropharynx cancer (larynx, n = 381; hypopharynx, n = 75; and oral cavity, n = 510). All cases were confirmed by histology or cytology. Most patients were male (81%), of white race (64%), ever smokers (85%), ever drinkers (82%), had a median age at diagnosis of 60 years, and only a basic education (54%). The majority of patients (66%) was diagnosed with stage IV disease, ranging from 53% for larynx to 83% for oropharynx disease. Median follow-up time for patients who died or survived was 0.9 years of 2.3 years, respectively. By October 31, 2017, 628 patients (48%) had died. Three-year overall survival was 53% for larynx, 47% for oral cavity, 40% for oropharynx, and 36% for hypopharynx disease. Main predictors of worse survival were late stage at diagnosis, older age, and underweight (body mass index < 18.5kg/m2) at diagnosis, with some variation according to tumor site. In a subset analysis of 156 patients with oropharynx cancer with available HPV16 E6 serology, those who were negative for HPV16 E6 had significantly lower 3-year survival (27% v 73%), and a corresponding 3.5 times higher mortality rate (adjusted hazard ratio, 3.5; CI, 1.2 to 10.6) than those who were positive for HPV16 E6. Conclusion Most patients presented with strikingly advanced disease, and stage at diagnosis was an important predictor of survival. The reasons for late diagnosis are unclear, and efforts to improve survival will largely depend on efforts to diagnose HNC at an early stage. Patients with HPV-related versus HPV-unrelated oropharynx cancer had better survival, which supports previous results from Europe and North America. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST No COIs from the authors.
A Bayesian Sensitivity Analysis to Partition Body Mass Index Into Components of Body Composition: An Application to Head and Neck Cancer Survival