A patient whose skin cancer had spread throughout his body has been given the all-clear after being injected with billions of his own immune cells.

Tests revealed that the 52-year-old man's tumours, which spread from his skin to his lung and groin, vanished within two months of having the treatment, and had not returned two years later.

Doctors attempted the experimental therapy as part of a clinical trial after the man's cancer failed to respond to conventional treatments.

The man is the first to benefit from the new technique, which uses cloning to produce billions of copies of a patient's immune cells. When they are injected into the body they attack the cancer and force it into remission.

Campaigners and scientists in the UK yesterday welcomed the breakthrough. "It's very exciting to see a cancer patient being successfully treated using immune cells cloned from his own body. While it's always good news when anyone with cancer gets the all-clear, this treatment will need to be tested in large clinical trials to work out how widely it could be used," said Ed Yong at Cancer Research UK.

Peter Johnson, chief clinician at the charity, added: "Although the technique is complex and difficult to use for all but a few patients, the principle that someone's own immune cells can be expanded and made to work in this way is very encouraging."

Cassian Yee at the Fred Hutchinson Cancer Research Centre in Seattle extracted immune cells from the patient and found that a small proportion of them, called CD4 T cells, naturally attacked a protein found on nearly three-quarters of the cancer cells. Using cloning techniques, Yee's team replicated these cells until they had more than 5bn of them.

When the cells were injected into the patient they immediately began attacking the cancer. Intriguingly, the patient's immune system gradually began a wider offensive, attacking all the cancer cells in the body, according to a report in the New England Journal of Medicine. Two months later medical scans failed to pick up any signs of cancer in the patient.

The team believes the treatment could be effective in around a quarter of skin cancer patients whose immune systems have cells that are already primed to attack their tumours. "For this patient we were successful, but we would need to confirm the effectiveness of therapy in a larger study," Yee added.

In an accompanying article Louis Weiner, director of the Lombardi Comprehensive Cancer Centre at Georgetown University, Washington, wrote that Yee's work "underscores the remarkable potential of the immune system to eradicate cancer, even when the disease is widespread".

The case showed that hopes to turn the immune system into a weapon against cancer was becoming a reality, Weiner added. "If the destination is not yet at hand, it is in sight. The endgame has begun."

Using the immune system to fight cancer could be much safer than existing treatments, which often have serious side effects.