A new platinum-based stomach cancer treatment has delivered encouraging results following a series of new tests.

The 2005 annual meeting of the American Society of Clinical Oncology heard how a new combination chemotherapy, using a drug called S-1, had yielded significant improvements on traditional platinum-based therapies.

S1 produced a "response" - when a tumour shrinks in response to treatment - in 13 of the 20 patients tested by chemical firm Taiho Pharma, representing a success rate of 65 per cent.

Oncologist Heinz-Josef Lenz, an associate professor of medicine at the Keck School of Medicine of the University of Southern California, said that the results also indicated patients experienced less severe side-effects than with traditional platinum-based drugs.

"We believe the therapy has the potential to not only fight cancer more effectively, but also is easier for cancer patients to deal with," he said.

The professor said that the results also corroborated a previous experiment with the drug, citing a Japanese team that recorded a 76 per cent success rate.

As many as 21,000 Americans are diagnosed with stomach cancer each year, with around half that number dying from the disease annually.