Doctors at the National Cancer Institute have dramatically increased the survival rate of patients stricken by one of the most devastating, fastest-growing of all cancers--soft-tissue sarcoma of the arms and legs.

By using three kinds of treatment--surgery, radiation and chemotherapy--in a sequential attack on these growths, they have achieved a 93 percent survival rate, about double the previous 40 to 50 percent.

In most cases they have also avoided an ordinarily standard part of the treatment: amputation of the affected limb or, often, of much more of the body in the invaded area.

The same kind of many-barreled, all-out attack should affect several other stubborn, hard-to-defeat cancers, perhaps including lung, colon and breast cancer, the NCI doctors predict.

Soft-tissue sarcomas are cancers that strike the connective and supportive and other tissues around bone, mostly in persons in their 20s to 40s, but also in children.

"These patients used to be dismembered," Dr. Vincent DeVita, NCI director, told a scientific advisory committee. "Most nonetheless had recurrences," mainly spread of the cancer to their lungs. "Then they would die a rather difficult pulmonary death. Now you are seeing people walking around."

The first report on the new advance was made to the advisory group at the National Institutes of Health in Bethesda by Dr. Steven Rosenberg, NCI surgery chief. The treatments were given at NIH's Clinical Center, its big research hospital, to patients referred by doctors all over the country.

The 93 percent three-year survival rate was accomplished in 63 patients aged 11 to 63. Most had minimal surgery -- to remove only the cancer, not the whole limb -- followed by radiation and "combined chemotherapy" using three anti-cancer drugs.

These patients did markedly better than a group treated by surgery plus radiation alone. They did just as well as a group whose surgery was complete amputation, followed by radiation and chemotherapy.

Some patients have now remained disease-free for more than four years. Long-term follow-ups will be needed to determine final results. But 80 per cent of recurrences of such cancers come in the first two years, Rosenberg said. So the final cures should not be drastically fewer than the current survivals.

Some patients, about one in five, will still require amputation, Rosenberg added. These are cases where the cancer has already spread beyond the boundaries where the surgeon can operate.

Chemotherapy, he also pointed out, inevitably has toxic or ill effects too. Many are temporary. But one of the chemicals, Adriamycin, may cause congestive heart disease --usually manageable by drugs -- in about 14 per cent of those who receive it.

The doctors are now seeking lower doses and other methods to eliminate or minimize such effects.