Tobacco Smoking and Increased Risk of Death and Progression for Patients With p16-Positive and p16-Negative Oropharyngeal Cancer

TLDR

Tobacco smoking is linked to poorer survival in oropharyngeal cancer, yet the magnitude of its impact on progression and death remains unclear. The study aimed to quantify how increasing tobacco exposure influences progression and mortality in patients with p16-positive and p16-negative oropharyngeal cancer. Researchers analyzed data from RTOG 9003 and RTOG 0129 phase III trials, determining p16 status via immunohistochemistry and measuring smoking exposure with a standardized questionnaire, then used Cox models to estimate associations with overall and progression-free survival. Higher tobacco exposure was associated with a 1% increase in risk of progression or death per pack‑year and a 2% increase per year of smoking, with smoking during radiotherapy doubling mortality risk and elevating second primary tumor risk, independent of p16 status.

Abstract

Purpose Tobacco smoking is associated with oropharynx cancer survival, but to what extent cancer progression or death increases with increasing tobacco exposure is unknown. Patients and Methods Patients with oropharynx cancer enrolled onto a phase III trial of radiotherapy from 1991 to 1997 (Radiation Therapy Oncology Group [RTOG] 9003) or of chemoradiotherapy from 2002 to 2005 (RTOG 0129) were evaluated for tumor human papillomavirus status by a surrogate, p16 immunohistochemistry, and for tobacco exposure by a standardized questionnaire. Associations between tobacco exposure and overall survival (OS) and progression-free survival (PFS) were estimated by Cox proportional hazards models. Results Prevalence of p16-positive cancer was 39.5% among patients in RTOG 9003 and 68.0% in RTOG 0129. Median pack-years of tobacco smoking were lower among p16-positive than p16-negative patients in both trials (RTOG 9003: 29 v 45.9 pack-years; P = .02; RTOG 0129: 10 v 40 pack-years; P < .001). After adjustment for p16 and other factors, risk of progression (PFS) or death (OS) increased by 1% per pack-year (for both, hazard ratio [HR], 1.01; 95% CI, 1.00 to 1.01; P = .002) or 2% per year of smoking (for both, HR, 1.02; 95% CI, 1.01 to 1.03; P < .001) in both trials. In RTOG 9003, risk of death doubled (HR, 2.19; 95% CI, 1.46 to 3.28) among those who smoked during radiotherapy after accounting for pack-years and other factors, and risk of second primary tumors increased by 1.5% per pack-year (HR, 1.015; 95% CI, 1.005 to 1.026). Conclusion Risk of oropharyngeal cancer progression and death increases directly as a function of tobacco exposure at diagnosis and during therapy and is independent of tumor p16 status and treatment.