A case-control study of glycemic index, glycemic load and dietary fiber intake and risk of adenocarcinomas and squamous cell carcinomas of the esophagus: the Australian Cancer Study

Background: Glycemic index (GI) and glycemic load (GL) have been investigated as etiologic factors for some cancers, but epidemiological data on possible associations between dietary carbohydrate intake and esophageal cancer are scant. This study examined the association between GI, GL, and other dietary carbohydrate components and risk of adenocarcinomas and squamous cell carcinoma of the esophagus accounting for established risk factors. Methods: We analyzed data from a population-based Australian case-control study (2002-05) comprising 299 adenocarcinoma (EAC), 337 gastro-esophageal junction adenocarcinoma (EGJAC), 245 squamous cell carcinoma (ESCC), and 1507 controls sampled from a population registry. Dietary information was obtained using a 135-item food frequency questionnaire (FFQ); GI and GL were derived from an Australian GI database. Multivariable logistic regression models were used to derive odds ratios (ORs). Results: All three case groups tended to have a lower intake of fiber, and significantly higher intake of fat, total energy, and alcohol (ESCC only) compared to controls. GI was unrelated to all histological types. Higher GL was not associated with risk of EAC and EGJAC, but was inversely associated with risk of ESCC (adjusted model, p(trend) = 0.006), specifically among men where we observed a 58% reduced risk of ESCC in the highest versus the lowest quartile. Increased intake of total carbohydrates and starch was related to similarly large risk reductions of ESCC. Fiber intake was strongly and inversely associated with risk of EAC, EGJAC and ESCC (all p(trend) <= 0.001), indicating risk reductions of 28%-37% per 10 g/day. Conclusions: This study suggests a reduced risk of esophageal SCC with higher GL level particularly in men, but provides no evidence for the role of GI in the development of esophageal cancer. In addition, increased fiber intake appears to be associated with lower risk of all histological types of esophageal cancer.