Abstract

Tobacco smoking is a major risk factor for head and neck cancer (HNC). Family history of cancer is also associated with HNC. This association lies in the difficulty in balancing the influence of hereditary vs shared environmental factors. We aimed to assess the role of smoking status of affected relatives on the risk of HNC. This study comprised 567 patients with HNC and 328 controls without cancer admitted in five centers in São Paulo State, Brazil, from 2005 to 2009; all of them had at least one parent or sibling with cancer of any site reported. Multivariate unconditional logistic regression was used to assess the effect of tobacco smoking in affected relatives on the risk of HNC. ORs were adjusted on socioeconomic status, tobacco smoking, alcohol drinking, age, sex and the number of relatives that experienced cancer. Having one or more smoker affected relative was associated with a higher risk of HNC (OR=2.39; 95% CI 1.69 to 3.37). This association remained high when stratification by cancer subsites was performed: oral cavity (2.11; 1.41 to 3.17), oropharynx (2.84; 1.54 to 5.23), larynx (4.05; 2.36 to 6.93). In conclusion, cancer affected relatives of HNC cases are more exposed to tobacco smoking than cancer affected relatives of controls. This finding suggests that lifestyle factors of parents or siblings with cancer history may play a role on the association between family history of cancer and HNC.