Ralph Steinman, the Canadian-born doctor who was awarded the Nobel Prize in medicine posthumously on Monday, used his landmark research in his own fight against cancer.

Steinman was diagnosed with pancreatic cancer four years ago. He had been working as a cell biologist at New York's Rockefeller University, which released a statement Monday saying that his life "was extended using a dendritic-cell based immunotherapy of his own design."

The 68-year-old passed away on Friday, and although the coveted prize isn't supposed to be awarded posthumously, the Nobel committee said it was unaware of his death so the decision would stand.

Steinman is credited with discovering dendritic cells, which help the immune system purge invasive micro-organisms. He shared the $1.5-million award with American Bruce Beutler and Jules Hoffmann of France.

Dr. Phil Gold, a friend and former colleague at Montreal General Hospital, noted that the life expectancy for those diagnosed with pancreatic cancer is "weeks to months." But Steinman lived four years after his diagnosis.

"It's beyond the norm… something else went on to make this occur," Gold told CTV News. "I would like to believe it was the dendritic cells that he may have prepared himself… that allowed this to happen."

The findings by Steinman and his two fellow Nobel winners on how the body's immune system functions could be used widely in future to treat patients afflicted with infections, communicable diseases or cancer.

Steinman discovered dendritic cells in 1973. They're able to activate T-cells, which help antibodies and killer cells to ward off infections. They also have a type of memory that allows the body's immune system to better fight off attacks to which it has previously been exposed.

Beutler and Hoffmann were honoured for their discoveries about the first stages of immune responses, while Steinman was cited for discoveries that led to better understanding of the later stages.

It's not yet clear who will accept the award on Steinman's behalf at the award ceremony Dec. 10.

In a statement, his daughter Alexis Steinman said that his family is "so touched that our father's many years of hard work are being recognized with a Nobel Prize. He devoted his life to his work and his family, and he would be truly honored."

Prime Minister Stephen Harper said in a release that Canadians will mourn the loss, but will celebrate the "remarkable accomplishments" of Steinman and his colleagues.

"Thanks to their dedication, the boundaries of science and medicine have been expanded."

With files from The Canadian Press