A scientist who won the Nobel prize for medicine for his work on cancer, died of the disease just days before he could be told of the award.

Calling it "bittersweet" news, colleagues of Canadian-born Ralph Steinman at New York's Rockefeller University said on Monday he had prolonged his own life with a new therapy based on his prize-winning research into the body's immune system.

The 68-year-old physician, who joked last week with his family about hanging on until the annual prize declaration, died on Friday after a four-year battle with pancreatic cancer.

The Nobel committee was not told about his death until hours after it announced the 2011 award, to be shared by Steinman and two other scientists, Bruce Beutler of the US and Jules Hoffman from France whose work on the immune system has also driven ground-breaking possibilities for curbing infections and cancers.

He never knew his life's work had been crowned with the highest accolade science can bestow, becoming the first person in half a century to win a posthumous Nobel prize.

"We said to him, 'Hang on until Monday,'" Alexis Steinman, his daughter, said. "We joked, we said, 'You know you got to keep going until the Nobel.'"

Admitted to hospital last Sunday, he lost consciousness on Thursday and died surrounded by family the following day.

But Marc Tessier-Lavigne, Rockefeller University president, said his staff only heard of his death from the family about half an hour after news of the Nobel prize came out from Sweden.

'Great scientist'

Goran Hansson, the Nobel Committee secretary general, told Reuters: "I am, of course, saddened that Dr Steinman could not receive this news and feel that happiness."

"He was a great scientist."

The Nobel Committee spent the morning calling Steinman to offer the traditional congratulations only to discover they faced a "unique" situation.

After consultations on the fate of the prize, and money worth three quarters of a million dollars, they decided it would go to Steinman's heirs.

"The Nobel Prize shall not deliberately be awarded posthumously. However, the decision to award the Nobel Prize to Ralph Steinman was made in good faith, based on the assumption that the Nobel laureate was alive," the committee said.

His university said: "Steinman ... was diagnosed with pancreatic cancer four years ago, and his life was extended using a dendritic-cell based immunotherapy of his own design."

Steinman, whose research contributed to the launch last year of the first approved vaccine to kill tumours, was working until his final days, colleagues said.

Beutler and Hoffmann, studied the first stages of the body's immune responses in the 1990s.

Beutler, 53, is based at the Scripps Research Institute in La Jolla, California. Luxembourg-born Hoffmann, 70, conducted much of his work in Strasbourg.