There are only a handful of cancers that are commonly screened for in the U.S. — including breast cancer, cervical cancer, colorectal cancer, and prostate cancer — but it’s a different story in Asia, where stomach (or gastric) cancer is so prevalent that countries including Japan and Korea have national stomach cancer screening programs aimed at detecting and treating the disease earlier.
“The standard screening for stomach cancer is upper endoscopy, to take a look inside the stomach with a scope,” says University of Colorado Cancer Center member Martin McCarter, MD, professor of surgical oncology in the CU Department of Surgery. “There are other tests that are helpful as well, and those have to do with H. pylori, a bacteria that can inhabit the stomach.”
Common in Asian countries — it’s estimated that around 80% of the population there carries the bacteria, McCarter says — H. pylori is strongly associated with the development of stomach cancer.
“In the U.S., it's estimated that the number of people carrying that bacteria is much lower, maybe 10% or 20%, and it is largely asymptomatic,” McCarter says. “People would not know that they have it.”
Endoscopic advantage
The most accurate way to test for H. pylori is endoscopy and biopsy, McCarter says, though researchers are working on blood, stool and breath tests device to detect the bacteria. Often people with chronic acid reflux get an endoscopy to evaluate the esophagus, but the test can detect stomach cancer as well. If the cancer is detected early enough, it can be removed during the endoscopy in the same way that polyps are removed from the colon during a colonoscopy.
“You can treat it early, with much less morbidity associated with surgery,” says McCarter, active research interest group member at the Katy O. and Paul M. Rady Esophageal and and Gastric Center of Excellence at the CU Cancer Center.
It’s not only Asians living in Asia who are at higher risk for H. pylori and stomach cancer; Asian immigrants to America may remain at higher risk and should consider getting screened for the disease, McCarter says.
“If you are an Asian immigrant, you should discuss screening with your primary care physician,” he says.
Screening for stomach cancer is especially important because symptoms associated with the disease often don’t show up until the cancer is at an advanced stage.
“Unfortunately, most gastric cancer symptoms present pretty late,” McCarter says. “The tumor either causes bleeding, so people often present with anemia, or it causes some obstructive symptoms, so they can't eat as well. These tend to be nonspecific symptoms that point us toward a potential diagnosis of gastric cancer.”
Advances in treatment
The good news about stomach cancer is that rates of new cases have been slowly dropping over the past 10 years, though rates of early-onset stomach cancer are slightly up in people under 50, particularly women. For those who are diagnosed with the disease, there are new treatment options, McCarter says.
“The subgroup of patients with gastric cancer who have what's called ‘microsatellite instability or mismatch repair deficiency’ are potentially eligible for immunotherapy, which has had some spectacular responses and, in some cases, eliminated the need for surgery,” he says. “The limiting issue is that only about 5% of all gastric cancers have that microsatellite instability.
“There also are developments in the pipeline for targeted therapy in gastric cancer,” he adds. “These are medicines targeted to specific molecular changes in the tumor that we can detect and analyze. If the tumors have that defect, then we have specific targeted therapies to go after that tumor.”
