FAMILIAL RISKS OF SQUAMOUS-CELL CARCINOMA OF THE HEAD AND NECK - RETROSPECTIVE CASE-CONTROL STUDY

Objective-To determine the contribution of inheritance to the incidenc e of squamous cell carcinoma of the head and neck. Design-Historical c ohort study. First degree relatives of cases with squamous cell carcin oma of the head and neck made up the exposed cohort and first degree r elatives of spouses of cases made up the comparison unexposed cohort. Setting-Ear, nose, and throat clinic in a large metropolitan teaching hospital. Subjects-1429 first degree relatives of 242 index cases of s quamous cell carcinoma of the head and neck; as controls, 934 first de gree relatives of the spouses of 156 index cases. Main outcome measure s-Relative risk of developing squamous cell carcinoma in first degree relatives of cases compared with risk in first degree relatives of spo uses. Results-The adjusted relative risk for developing head and neck cancer if the index case had squamous cell carcinoma of the head and n eck was 3.79 (95% confidence interval 1.11 to 13.0). There were no sig nificantly increased risks associated with a family history of cancer at other sites. The adjusted relative risk for squamous cell carcinoma of the head and neck was 7.89 (1.50 to 41.6) in first degree relative s of patients with multiple primary head and neck tumours. Conclusions -These data suggest that genetic factors are important in the aetiolog y of head and neck cancer, in particular for patients with multiple pr imary cancers. Given the prolonged exposure of these subjects to carci nogens, these genetic factors may have a role in modifying carcinogen activity or in host resistance to carcinogens. Inherited factors may b e important in persons with environmentally induced cancers.