WEDNESDAY, Aug. 3 (HealthDay News) -- Stomach cancer tumors have genetic differences, which determine how they respond to treatment, researchers have found.

In identifying two distinct versions of the disease, scientists found that a certain regimen of chemotherapy is more effective on one tumor type, while another drug works best on the other. The study authors said their findings would help doctors more effectively treat gastric cancer patients.

"Our study is the first to show that a proposed molecular classification of gastric cancer can identify genomic subtypes that respond differently to therapies, which is crucial in efforts to customize treatments for patients," study senior author Dr. Patrick Tan, associate professor in the Cancer and Stem Cell Biology Program at the Duke-National University of Singapore (NUS) Graduate Medical School, said in a university news release.

A microscopic pathology test developed in the 1960s, known as the Lauren classification, is a general description (either intestinal or diffuse) of how well the tumor cells clump together. The Singapore-based team at the Duke-NUS Graduate Medical School, however, was able to distinguish gastric cancer tumors where the Lauren test could not.

"There is a general assumption in the field that intestinal and diffuse gastric cancers [as classified by Lauren] represent two very different versions of gastric cancer, and now genomic data confirms this by demonstrating that the two genomic subtypes have very different molecular patterns," said Tan.

In profiling 37 stomach cancer cell lines, the researchers found two distinct patterns. Moreover, in accurately defining these tumor subtypes, they were also able to observe differences in how well each responded to chemotherapy.

"The exact mechanistic reasons for this difference are currently unclear, and this is an area that we are actively working on," noted Tan, adding that the researchers are working to find more specific vulnerabilities to drugs.

The researchers said they plan further research in which gastric cancer tumors will be genetically profiled to determine the most effective treatment.

The study findings were published in the Aug. 1 edition of Gastroenterology.

More information

The American Cancer Society has more about stomach cancer.