An observational study to assess changes in social inequality in smoking-attributable upper aero digestive tract cancer mortality among Canadian males between 1986 and 2001.

ABSTRACT

BACKGROUND: Tobacco and low socioeconomic status have been acknowledged as potential risk factors for upper aero-digestive tract (UADT) cancers in North America. In context of reducing adult male smoking prevalence (by over 50%), in the past few decades in Canada, this study tried to document changes in smoking-attributable UADT cancer mortality rates, among Canadian males of different social strata, between 1986 and 2001. METHODS: The contribution of smoking to UADT cancer mortality was estimated indirectly by using lung cancer mortality as an indicator of the accumulated mortality from smoking in a population. This method was applied to UADT cancer death rates of 35-69 year old socially stratified males. Data, stratified by neighborhood income quintile, could be obtained from Statistics Canada, for four census years, 1986, 1991, 1996, and 2001. RESULTS: A total of 2704 male deaths were analyzed. Between 1986 and 2001, UADT cancer deaths reduced by 30% (32 to 22 per 100,000) but the proportion of these deaths attributable to smoking reduced much more, by 41% (22 to 13 per 100,000). In the span of fifteen years, absolute social inequality (measured by rate difference between the highest and the lowest stratum) in smoking-attributable male UADT cancer mortality in Canada reduced by 47% and relative social inequality (measured by rate ratios) reduced by 9%. CONCLUSION: The present analyses reveal that between 1986 and 2001, smoking-attributable UADT cancer mortality rates among adult males (35-69 years) in Canada reduced in all social strata and the social inequalities in these rates have narrowed. Analysis of more current data will be of interest to confirm these trends.