(HealthDay)—The incidence of early-onset gastric cancer has been increasing in the United States, and it seems to be distinct clinically and genetically from late-onset gastric cancer, according to a study recently published in Surgery.

John R. Bergquist, M.D., from the Mayo Clinic in Rochester, Minnesota, and colleagues examined clinical and genomic characteristics and risk factors for early-onset versus late-onset gastric cancer using data from the Surveillance, Epidemiology, and End Results database (1973 to 2015), the Behavioral Risk Factor Surveillance Survey, and The Cancer Genome Atlas.

The researchers found that during the study period, the incidence of early-onset gastric cancer increased, now comprising more than 30 percent of all gastric cancer in the United States. Compared with late-onset disease, early-onset gastric cancer was associated with higher grade (55.2 versus 46.9 percent), signet-ring cells (19.0 versus 10.4 percent), diffuse histology (25.7 versus 15.0 percent), and metastatic disease (49.5 versus 40.9 percent). Late-onset gastric cancer was more likely to be microsatellite instability subtype (18.6 versus 5.6 percent), whereas early-onset disease was more likely to be Epstein Barr virus (7.7 versus 5.1 percent) or genomically stable (22.5 versus 8.1 percent) subtype. Compared with late-onset gastric cancer, risk factors for gastric cancer were less correlated with early-onset disease.

“Typically, we see stomach cancer being diagnosed in patients in their 70s, but increasingly we are seeing 30- to 50-year-old patients being diagnosed,” a coauthor said in a statement. “Hopefully, studies like this will raise awareness and increase physician suspicion of stomach cancer, particularly in younger patients.”