Robert Clark cheers with fans after singing the national anthems before the Edmonton Oilers and Florida Panthers play Game 1 of the NHL Stanley Cup Final, in Edmonton, on Wednesday, June 4, 2025. THE CANADIAN PRESS/Darryl Dyck

EDMONTON — The Edmonton Oilers' anthem singer who became a fan favourite for belting out O Canada in the stands with fans says he's staying optimistic after he was diagnosed with leukemia.

Robert Clark shared the news Sunday in a video posted online, saying he'll be going through treatment beginning next month and hopes not to miss too many games.

Clark said he was diagnosed with hairy cell leukemia, which he describes as treatable and sounding "worse than it is."

"Nobody wants to be told they have cancer," he said. "Not fun, but I'm very optimistic."

The Canadian Cancer Society says hairy cell leukemia is a relatively rare form of cancer that affects white blood cells, a key part of the immune system that helps fight off infections.

Clark said he began having joint pain in August, and his diagnosis came after a series of tests, which included a bone marrow biopsy.

He said the cancer has caused his spleen to swell on top of regular bouts of fatigue.

"It also leads to a very weakened immune system, so I don't go out much just to avoid getting anything if I can."

The professional opera singer gained prominence nearly a decade ago when he started singing O Canada and the U.S. anthem while standing in the crowd rather than on the ice during the team's 2017 playoff series against the Anaheim Ducks.

It's a tradition Clark has continued through the Oilers' playoff runs since, including the back-to-back trips to the Stanley Cup final these past two seasons.

Fans were quick to share words of encouragement for Clark online, as was the team, which wrote, "You got this, Robert!"

The singer said it's possible he might miss a few of the team's games while he goes through treatment, but he said the worst of it will happen during a long road trip for the Oilers in November.

"The first week is going to suck, and then it get just gets better and better," he said of the treatment.

Clark didn't immediately respond to an interview request.

This report by The Canadian Press was first published Oct. 20, 2025.

News from © The Canadian Press, 2025