(ChemotherapyAdvisor) – Tobacco exposure increases cancer progression and death in patients with oropharygeal cancer, according to a team of U.S.-based researchers. This conclusion is based on a study entitled “Tobacco Smoking and Increased Risk of Death and Progression for Patients With p16-Positive and p16-Negative Oropharyngeal Cancer,” which was published in the Journal of Clinical Oncology on June 10.

In the study, the investigators aimed to assess the correlation between increased exposure to tobacco and increased progression or death from oropharyngeal cancer. This Phase 3 trial evaluated patients 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,” the investigators wrote.

Median pack-years of tobacco smoking were lower among p16-positive than p16-negative patients in both trials (RTOG 9003: 29 vs. 45.9 pack-years; P=.02; RTOG 0129: 10 vs. 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).

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The investigators concluded that “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.”