Occupation as a measure of life course socioeconomic position and the risk of oral cancers in India

OBJECTIVES

Evidence suggests that different indicators of socioeconomic position (SEP) contribute to oral cancer risk. Occupational status, as a measure of SEP, may be able to capture aspects of social hierarchy in societies in which employment is highly correlated with other social structures such as caste systems. Often in such societies, the life course of an individual is also influenced by this hierarchy. However, the influence of life course occupational status on the risk of oral cancer is not well understood. This study aims to identify the life course model that is best supported by the data using life course SEP-as represented by occupation-on oral cancer risk in a population in the South of India.

METHODS

Data from the HeNCe Life study, Indian site were used. Incident oral cancer cases (N = 350) were recruited from two major referral hospitals in Kozhikode, Kerala, South India, from 2008 to 2012. Controls (N = 371), frequency-matched by age (5 years) and sex were recruited from the outpatient clinics at the same hospitals as the cases. Life grid-based structured interviews collected information on an array of exposures throughout the life course of the participant. Occupation was coded with the 1988 International Standard Classification of Occupations, transformed to the simplified European Socioeconomic Classification, and further dichotomized into advantageous and disadvantageous SEP at three different life periods (childhood, early adulthood and late adulthood). The analysis was conducted using the Bayesian relevant life course exposure model with a Dirichlet noninformative prior and a weakly informative Cauchy prior to the overall lifetime effect and confounders.

RESULTS

Participants in disadvantaged SEP throughout their life had 3.6 times higher risk of oral cancer than those in advantaged SEP (OR = 3.6; 95% CrI = 1.6-7.2), after adjusting for potential confounders. While the crude and sex- and age-adjusted models showed a clear childhood sensitive period for this risk, the model further adjusted for behavioural factors could not distinguish the specific life course period best explained by data.

CONCLUSION

Occupation status alone could provide a similar overarching risk estimate for oral cancer to those obtained from more complex measures of SEP.

Disadvantageous Socioeconomic Position at Specific Life Periods May Contribute to Prostate Cancer Risk and Aggressiveness

Background: Previous studies on socioeconomic position (SEP) and risk of prostate cancer (PCa) have produced contradictory results. Most measured SEP only once during the individuals' life span. The aim of the study was to identify life course models that describe best the relationship between SEP measured during childhood/adolescence, early- and late-adulthood, and risk of PCa overall as well as according to tumor aggressiveness at diagnosis. Methods: We used data from a population-based case-control study of PCa conducted in the predominantly French-speaking population in Montreal, Canada. Cases (n = 1,930) with new, histologically-confirmed PCa were ascertained across hospitals deserving the French-speaking population in 2005-2009. Controls (n = 1,991), selected from Quebec's list of French-speaking electors, were frequency-matched to cases (±5 years). In-person interviews collected information on socio-demographic and lifestyle characteristics, and a complete occupational history. Measures of SEP during childhood/adolescence included parents' ownership of a car and father's longest occupation, while the subject's first and longest occupations were used to indicate early- and late-adulthood SEP, respectively. We used the Bayesian relevant life course exposure model to investigate the relationship between lifelong SEP and PCa risk. Results: Cumulative exposure to disadvantageous SEP was associated with about a 50% increase in odds of developing PCa. Late-adulthood SEP was identified as a sensitive period for aggressive PCa. Childhood/adolescence SEP based on parents' ownership of a car was associated with non-aggressive PCa. Associations were independent from PCa screening. Conclusion: Disadvantageous SEP over the life course was associated with higher PCa incidence, with consistent evidence of sensitive time periods for cancer aggressiveness. The mechanisms through which disadvantageous SEP relates to PCa risk need to be further elucidated.