Genetic differences between two types of stomach cancer could help doctors select the most effective treatment for a patient's tumour, say Singapore researchers. The research team used a new, better method of classifying tumours to distinguish 'diffuse' from 'intestinal' tumours.

Chemotherapy drugs 5-fluorouracil and oxaliplatin were more effective treatments for intestinal tumours, and cisplatin was more effective for patients with diffuse tumours.

'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 customise treatments for patients', said senior author Dr Patrick Tan from the Duke-National University of Singapore.

Researchers have long known that patients respond differently to treatments, according to a Duke University Medical Centre press release. But: 'Most gastric cancer patients are still being treated with a common one-size-fits-all regimen', Dr Tan said.

Stomach cancers are categorised using the Lauren classification system – a microscopic test that describes how well cells are clumped together. But the team found the Lauren classification was not reliable at distinguishing cancer subtypes among 37 stomach cancer cell lines.

In 36 percent of cases, an analysis of gene activity (expression) distinguished the subtypes - either intestinal or diffuse - when the Lauren classification could not. In 64 percent of cases, the genetic subtypes validated the Lauren classifications. These results were confirmed using samples taken from 521 stomach cancer patients.

'The exact mechanistic reasons for this difference are currently unclear, and this is an area that we are actively working on', remarked Dr Tan.

With his team, Dr Tan has launched a new clinical trial where patients with stomach cancer will be treated based on the genetic profile of their tumours.