Cheek was forced to take time off to undergo surgery on June 12, 2004, to remove a brain tumor. Following the surgery, Cheek was able to call some Blue Jays home games while undergoing chemotherapy, but was replaced on the road by various guest announcers. For a time, it seemed he had recovered and would be able to resume calling Blue Jays games in 2005. However, the cancer returned and he required further treatment at Toronto's Mount Sinai Hospital and Toronto Western Hospital.
