Socio-economic status and upper aerodigestive tract cancer.

Design: A multicentre case-control study. CASE/CONTROL SELECTION: Cases were defined as those diagnosed with primary squamous cell tumours of the UADT between 2002 and 2005. Diagnoses included malignant cancers of the oral cavity, oropharynx, hypo-pharynx, larynx or oesophagus. Incident cases were ascertained through weekly monitoring of head and neck cancer clinics in hospital departments and confirmed by pathology department records. Controls were frequency-matched to cases by sex and age (five-year groups). In the UK centres, population controls were randomly selected from the same community medical practice list as the corresponding cases. Specifically, for each case, a total of 10 controls were selected, matched by age and sex. Potential controls were approached in a random order one at a time until one agreed to participate. In all other centres, hospital controls were used. Only controls with a recently diagnosed disease were accepted, and admission diagnoses related to alcohol, tobacco or diet were excluded. Eligible diagnoses included endocrine and metabolic; genito-urinary; skin, subcutaneous tissue and musculoskeletal; gastro-intestinal; circulatory; ear, eye and mastoid; nervous system diseases; trauma and plastic surgery. The proportion of controls within a specific diagnostic group could not exceed 33% of the total in any particular centre.

Data Analysis: Personal interviews collected information on demographics, lifetime occupation, history, smoking, alcohol consumption and diet. Socioeconomic status was measured by education, occupational social class and unemployment. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using unconditional logistic regression.

Results: When controlling for age, sex and centre, significantly increased risks for UADT cancer were observed for those with low versus high educational attainment OR = 1.98 (95% CI 1.67, 2.36). Similarly, for occupational socioeconomic indicators--comparing the lowest versus highest International Socio-Economic Index (ISEI) quartile for the longest occupation gave OR = 1.60 (1.28, 2.00); and for unemployment OR = 1.64 (1.24, 2.17). Statistical significance remained for low education when adjusting for smoking, alcohol and diet behaviours OR = 1.29 (1.06, 1.57) in the multivariate analysis. Inequalities were observed only among men but not among women and were greater among those in the British Isles and Eastern European countries than in Southern and Central/Northern European countries. Associations were broadly consistent for subsite and source of controls (hospital and community)

Conclusions: Socioeconomic inequalities for UADT cancers are only observed among men and are not totally explained by smoking, alcohol drinking and diet.