A Case-Control Study to Evaluate Environmental and Lifestyle Risk Factors for Esophageal Cancer in Tanzania

Background East Africa is affected by a disproportionately high burden of esophageal squamous cell carcinoma (ESCC). Methods We conducted an incident case-control study in Dar es Salaam, Tanzania with 1:1 matching for gender and age. A questionnaire evaluated known and putative risk factors for ESCC. Cochran-Mantel-Haenszel and multivariable conditional logistic regression analyses were applied to evaluate associations with ESCC risk, with adjustment for geographic zone. Results Of 471 cases and 471 controls, the majority were male (69%); median ages were 59 and 55, respectively. In a multivariable logistic regression model, a low International Wealth Index (IWI) score (OR 2.57, 95% CI 1.41-4.68), former smoking (OR 2.45, 95% CI 1.46-4.13), second-hand smoke in the household (OR 1.67, 95% CI 1.01-2.77), daily spicy chilies (OR 1.62, 1.04-2.52), and daily salted foods (OR 2.02, 95% CI 1.06-3.85) were associated with increased risk of ESCC. Daily consumption of raw greens (OR, 0.36, 95% CI 0.16-0.80), fruit (OR 0.47, 95% CI 0.27-0.82), and smoked fish (OR 0.31, 95% CI 0.15-0.66) were protective. Permanent residence in the Central (OR 5.03, 95% CI 2.16-11.73), Northern-Lake (OR 2.40, 95% CI 1.46-3.94), or Southern Highlands zones (OR 3.18, 95% CI 1.56-6.50) of Tanzania were associated with increased risk compared to residence in the Eastern zone. Conclusions Low IWI score, smoke exposure(s), geographic zone, and dietary factors were associated with risk for ESCC in Tanzania. Impact These findings will inform the development of future hypothesis-driven studies to examine risk factors for the high burden of ESCC in East Africa.