Risk Factors Associated With Early-Onset Esophageal Cancer in Tanzania.

PURPOSE: Eastern Africa is one of several regions affected by high incidence rates of esophageal squamous cell carcinoma (ESCC). A unique epidemiologic feature of ESCC in Eastern Africa is the high incidence in young people, with one-third of cases diagnosed at age < 45 years. This study aimed to investigate risk factors for early-onset ESCC in Tanzania through a secondary analysis of a matched case-control study. MATERIALS AND METHODS: From 2013 to 2015, ESCC cases were recruited at Muhimbili National Hospital and Ocean Road Cancer Institute in Dar es Salaam, Tanzania. Hospital controls were identified from patients with nonmalignant conditions and matched 1:1 for sex and age (± 10 years). Questionnaires were used to assess sociodemographic characteristics and environmental, dietary, and lifestyle risk exposures. Multivariate logistic regression models were used to estimate age-specific odds ratios of ESCC for exposures among participants age 30-44 and ≥ 45 years. RESULTS: A total of 471 cases and 471 controls were enrolled. Among cases, 100 (21%) were < 45 years. Multiple exposures were identified as risk factors for early-onset ESCC, several of which were unique to this age group, including infrequent teeth cleaning, secondhand tobacco smoke exposure, and pest infestation of grain and/or nuts. Lower socioeconomic status, family history of ESCC, tobacco smoking, home-brewed alcohol consumption, home storage of grain and/or nuts, and use of firewood for cooking were associated in the older but not the younger age group. Hot beverage intake was associated with increased ESCC risk in both age groups. CONCLUSION: Our results suggest that ESCC risk factors in Tanzania vary between age groups. With the data currently available, environmental and behavioral risk factors appear to play an important role in the high incidence of ESCC among young people.

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% confidence interval (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 with 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.See related commentary by McCormack et al., p. 248.

Characteristics of Esophageal Cancer Cases in Tanzania.

PURPOSE: Age-standardized incidence rates for esophageal cancer (EC) in East Africa have been reported as disproportionately high compared with the worldwide incidence of nine per 100,000 population. This study aimed to characterize EC cases seen at Muhimbili National Hospital and Ocean Road Cancer Institute in Dar es Salaam, Tanzania. METHODS: Demographic, clinical, and treatment variables were abstracted from charts of patients who received care for a diagnosis of EC at one or both institutions between 2011 and 2013. Categorical data were summarized as frequency counts and percentages. Continuous data were presented as medians and ranges. To compare men and women, Pearson's χ2 and two-sample t tests were applied. RESULTS: Seven hundred thirty-eight unique cases of EC were identified, of whom 68% were men and the median age was 60 years (range, 19 to 95 years). Notably, 93 cases (13%) were ≤ 40 years old at diagnosis. Squamous cell carcinoma was the dominant histology, comprising 90% of cases with documented histopathology. However, 34% of cases with a diagnosis of EC were not pathologically confirmed. The stage was documented as locoregional in 4% of cases, locally advanced in 20% of cases, metastatic in 14% of cases, and unknown in 63% of cases. Of 430 patients who received treatment at Ocean Road Cancer Institute, 76% were treated with radiation, 44% were treated with chemotherapy, 3% underwent a cancer-related surgical procedure, and 10% of cases received no cancer-directed therapy. The median overall survival for all patients was 6.9 months (95% CI, 5.0 to 12.8), regardless of stage at presentation. CONCLUSION: Between 2011 and 2013, cases of EC represented a large clinical burden at both institutions.