Bottom Line: Acid reflux was associated with cancer of the respiratory and upper digestive tracts in older adults.
Why The Research Is Interesting: Cancers of the respiratory and upper digestive tracts account for more than 360,000 deaths worldwide each year. These cancers are thought to be caused by various factors, including chronic inflammation. Studies examining a link between the inflammatory condition gastroesophageal reflux disease (GERD or acid reflux) and the development of cancer in the respiratory and upper digestive tracts have had conflicting results.
Who and When: 13,805 patients (66 or older) with cancer of the respiratory and upper digestive tracts and 13,805 patients without cancer; patient information came from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, a registry of cancer patients and their treatments and outcomes, between 2003-2011.
What (Study Measures): Cancer of the respiratory and upper digestive tracts
How (Study Design): This was a case-control observational study. Patients with cancer of the respiratory and upper digestive tracts (outcome) were compared to those without cancer to examine whether GERD (exposure) was associated with cancer. Researchers were not intervening for purposes of the study and cannot control natural differences that could explain the study findings.
Authors: Edward D. McCoul, M.D., M.P.H., Tulane University School of Medicine, New Orleans, and coauthors
Results: GERD was associated with cancer of the throat, tonsils, and parts of the sinuses.
Study Limitations: Data about patient tobacco and alcohol use, which are the most well-established risk factors for cancer of the respiratory and upper digestive tracts, were not reported in the database. Diagnoses were based on ICD-9 codes which are used for billing rather than clinical purposes.
Study Conclusions: GERD was associated with cancer in older adults in the respiratory and upper digestive tracts. This association requires further study to determine causality and to possibly identify an at-risk population so surveillance can be improved and treatment initiated earlier.