Clustering of Esophageal Cancer: Differences by Histology

Abstract

I read with great interest the article published in the August 2022 issue of Gastroenterology by Ma et al, “Factors Associated With Geographic Disparities in Gastrointestinal Cancer Mortality in the United States.”1Ma C. et al.Gastroenterology. 2022; 163: 437-448.e1Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar The authors demonstrated geographic variability in the mortality from 4 cancers, and that the known patient and structural factors account for up to 61% of that variability. However, the results regarding esophageal cancer are difficult to interpret because there are 2 histologic subtypes of esophageal cancer—adenocarcinoma and squamous cell carcinoma—each with distinct risk factors. Most importantly, adenocarcinoma is the predominant type in White Americans and squamous cell carcinoma the predominant type in Black Americans. Unfortunately, the platform used, the Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research (CDC WONDER), does not provide information on histology. We previously used the National Program of Cancer Registries to demonstrate that state-level disparities in esophageal adenocarcinoma mortality among non-Hispanic White men is similar to what Ma et al found for esophageal cancer mortality overall.2Rubenstein J.H. et al.Dis Esophagus. 2018; 32: doy081Google Scholar However, there is a very different pattern for esophageal squamous call carcinoma mortality among non-Hispanic Black men, with the highest-risk states in the southeastern U.S. and bordering the Mississippi River (very similar to the patterns that Ma et al observed for pancreatic and colorectal cancer risk). Furthermore, we examined the county-level mortality from esophageal cancer among non-Hispanic White men using the Vital Statistics Cooperative Program Multiple Causes of Death Files (this analysis was not informative for Black men owing to small numbers of cases in individual counties). Even after adjusting for known risk factors, there were areas of high esophageal cancer mortality among non-Hispanic White men stretching from the eastern Great Lakes to New England, as well as western Washington and northern Oregon. Since that publication, Cattelan et al published an analysis of clustering of esophageal cancer incidence by histologic subtype within Canada by postal code.3Cattelan L. et al.Cancer Med. 2020; 9: 401-417Crossref PubMed Scopus (13) Google Scholar They found that the risk of esophageal adenocarcinoma mirrored what we had observed south of the border, with clusters in southern Vancouver Island (which borders Washington), eastern Lake Ontario (across from northern New York), and Nova Scotia and Prince Edward Island (Gulf of St Lawrence, east of Maine). Ma et al admirably focus on issues regarding access to care, and that may be particularly important for the cluster of esophageal cancer mortality among non-Hispanic Black men. But our data and the data from Cattelan et al suggest that there may also be an unknown environmental factor that could be driving the pathogenesis of esophageal adenocarcinoma. The high-risk areas appear to be adjacent to waterways with a long history of pollution. Further research is needed to identify whether such pollutants could be contributing to the rising incidence of esophageal adenocarcinoma, both locally in those high-risk areas and potentially elsewhere. Factors Associated With Geographic Disparities in Gastrointestinal Cancer Mortality in the United StatesGastroenterologyVol. 163Issue 2PreviewThe highest rates of death from gastrointestinal cancers occur in rural counties and in the Southeastern United States, with differences in county-level mortality from esophagus, stomach, pancreas, and colon cancer being associated with higher rates of smoking, diabetes, and obesity. Full-Text PDF