ATLANTA — An Oregon man, given less than a year to live, had a complete remission of advanced deadly skin cancer after an experimental treatment that revved up his immune system to fight the tumors.

The 52-year-old patient's dramatic turnaround was the only success in a small study, leading doctors to be cautious in their enthusiasm. However, the treatment, reported in today's issue of the New England Journal of Medicine, is being counted as the latest in a small series of successes involving immune-priming treatments against deadly skin cancers.

"Immunotherapy has become the most promising approach" to late-stage, death-sentence skin cancers, said Dr. Darrell Rigel, a dermatology researcher at the New York University Cancer Institute in New York who had no role in the research.

Still, the immune-priming experiments have yet to yield a consistent therapy. Even researchers who worked on the experiment involving nine patients and just one success are quick to couch the result. "This is only one patient," said study co-author Dr. Cassian Yee of the Fred Hutchinson Cancer Research Center in Seattle.

And two years after his remarkable recovery, the patient fell out of contact with researchers, and scientists do not know his current condition. The man, who lives in a small town in Oregon, has declined media interviews.

Melanoma is a cancer in the skin cells that make pigments and cause skin to tan, as part of the body's attempt to protect itself from ultraviolet radiation in sunlight. Cancer begins when radiation overloads and damages the cells, causing mutations.

About 62,000 news cases are diagnosed in the United States each year, and there are about 8,000 melanoma deaths.

When caught early, melanomas can be easily treated by surgically removing the cancerous patch of skin. But "once it has spread, basically nothing works," Rigel said.

Recently, however, scientists began thinking they might have another option — helping the body's immune system.

Doctors had long thought that immune system cells, which so effectively attack foreign threats like viruses, were giving a pass to cancer cells. The theory was that because cancers cells are generated by the body, the immune system perceived them as part of the body.

But about 20 years ago, some scientists discovered that immune cells could latch onto and attack skin cancers.

The Oregon man had a melanoma on his back before it had spread to his groin and right lung. He was treated in July 2005. Two months after the treatment, advanced scans of his body revealed no tumors. Two years later, he had no symptoms.

And there were no harmful side effects. What's more, an analysis showed that his immune system had targeted not only one type of protein target on cancer cells, but two others as well.