Terry Fox's father, Rolland (Rolly) Fox, has been diagnosed with lung cancer.
The family made the announcement Tuesday in a statement on the Terry Fox Foundation website.
"It is with heavy hearts that we wish to share with Terry Foxers from coast to coast and around the world that our Dad and Grandfather, Rolland (Rolly) Fox, has recently been diagnosed with lung cancer," said the statement.
"He remains in very good spirits, confirmed by the dated and overused humour we are forced to endure."
Rolly Fox will turn 81 in March. The post states he started smoking at age 19 but quit 30 years ago.
A resident of Port Coquitlam, Fox is described as a "behind-the-scenes believer of Terry's mission for 36 years."
Betty Fox, Terry's mom, passed away in 2011.
Terry Fox is one of the most beloved Canadians in history because of his 1980 Marathon of Hope — an attempt to run across Canada on a prosthetic leg to raise money for cancer research.
Fox lost his right leg to cancer in 1977 when he was 18.
After running 5,000 kilometres Terry was forced to stop after the cancer spread to his lungs. He died on June 28, 1981 at age 22.
To date, over $650-million has been raised for cancer research through the Terry Fox Foundation and the Terry Fox Run, staged annually across Canada and around the world.