In the first case of its kind, doctors have treated a cancer patient by injecting him with billions of his own immune cells, a development that projects the huge power of gene therapy for the killer disease.

According to reports in the New England [Images] Journal of Medicine, United States researchers treated a 52-year-old man of melanoma by cloning cells from the patients own defence system and injecting them back into his body, in a process known as immunotherapy. The man was free from tumours within eight weeks of undergoing the procedure. After two years he is still free from the disease which had spread to his lymph nodes and one of his lungs.

"For this patient we were successful, but we would need to confirm the effectiveness of therapy in a larger study," said Cassian Yee, who led the team at the Fred Hutchinson Cancer Research Centre in Seattle. The treatment, which is extremely expensive at this stage of development, showed that vast numbers of immune cells in the body can be safely and effectively used to treat skin cancer, The Daily Telegraph of Britain said on Thursday.

The treatment raises hopes that this approach could not only offer a more effective treatment for skin cancer, or melanoma, but be applied to other cancers too. Larger, more elaborate, trials are now under way, the report said.