Doctors reported finding the first tentative evidence that chemotherapy may be able to help control lung cancer, the nation's leading cancer killer.

Four studies presented at a medical conference produce at least a hint that platinum-based drugs, combined with radiation and sometimes surgery, may help prolong patients' survival.None of the research suggests anything close to a cure for lung cancer, but doctors are encouraged by any improvement in a disease in which survival is measured in months, rather than years.

"There is no effective therapy for the vast majority of patients," said Dr. Robert Capizzi of Wake Forest University in Winston-Salem, N.C.

He said this makes the latest research, presented this week at the annual meeting of the American Society of Clinical Oncology, potentially important.

"There is the possibility that drugs may, for some subset of patients, have important effects," he said. "We don't have a prescription to be offered to the masses. We have important new leads for controlled clinical trials."

About 150,000 new cases of lung cancer are diagnosed each year. The four studies were conducted on people with non-small cell lung cancer, which accounts for about three-quarters of all cases.

The most encouraging results were presented by Dr. Robert O. Dillman of the Scripps Clinic of San Diego.

Like the other studies, his was conducted on people whose cancer was too extensive to be removed surgically but had not spread beyond the chest. Typically, such people are treated with radiation, which slows but does not stop the disease.

He treated 240 patients with radiation and chemotherapy or with radiation alone.

He estimated that half of the patients receiving the combination would still be alive after one year, compared with one-third of those who got only radiation.

"Our study is the first to show that chemotherapy may help at all in non-small cell lung cancer," Dillman said.

While the treatment may represent an advance, he said, "this is not going to be enough. More clinical trials will be needed to improve survival in this disease."

Dr. Roscoe Morton the North Central Cancer Treatment Group in Rochester, Minn., conducted a similar study using different chemotherapy drugs. However, in this attempt, the drugs did not help people live longer.

"We were not able to influence the outcomes by chemotherapy in addition to radiation," he said.

The other studies used chemotherapy plus radiation to shrink tumors so they could be removed surgically.

In one, directed by Dr. Gary M. Strauss of St. Vincent Hospital in Worcester, Mass., doctors were able to completely remove tumors from 10 of 41 patients treated.

He said the patients' median survival is 17 months, and "there is a suggestion that this approach might be associated with longer survival."

A smiliar study was conducted by Dr. Paul L. Weiden and colleagues at Virginia Mason Medical Center in Seattle on 69 patients. He said there was no clear evidence that patients there did better.