Factors Associated with Esophageal Cancer by Altitude Differences in Tanzania: A Comparative Study

Abstract

Background: Esophageal cancer is the 8th most common cancer and the 6th cause of cancer deaths in the world. There is a discrepancy in the distribution of the disease in highlands and lowlands. In Tanzania, there is a trend that shows the prevalence of the disease is increasing in lowlands. This change seems to be due to the bias of some risk factors that have become more common in lowlands. However, there is no current information in Tanzania on the distribution of risk factors for esophageal cancer between lowlands and highlands. Aim of the study: Is to compare the occurrence of risk factors between EC patients coming from lowlands with those coming from highlands Methodology: A prospective comparative hospital-based study was conducted among patients at Muhimbili National Hospital and Ocean Road Cancer Institute. The subjects were categorized into groups of those coming from highland areas and those coming from lowland areas. Information on demography and risk factors for esophageal CA was collected. The data was then analyzed to calculate the Odds ratios of the presence of individual risk factors in low land areas compared to highland areas. Results: A total of 310 participants were enrolled in the study. There were 136 participants from the lowlands and 174 from highlands. The mean age of participants was 57.4 ± 14.5 years. Squamous cell carcinoma was the most common histological type in both lowlands and highlands. Patients from highlands had 1.9 odds of drinking alcohol compared to patients from lowlands (p-value 0.006, CI 1.2 – 3.1). The commonest risk factors in lowlands were drinking hot beverages at 97.8% while the commonest risk factor in highlands was the consumption of red meat (97.7%). Conclusions: In Tanzania, esophageal cancer is still a predominantly a highlands disease however the incidence in lowlands is on the rise. Most of the risk factors profiles do not differ significantly between patients from highlands and lowlands except alcohol intake and red meat consumption which are more common in highlands and taking of hot drinks which is most common in lowlands.