Donovan said he has been battling leukemia for nearly 11 years. He will now need a bone marrow transplant.
"For close to 11 years now, I have been going through all various different kinds of treatment, but now I need a different kind of treatment," Donovan told his viewers. "So next week, I will begin the very laborious process of having a bone marrow transplant, so that's going to keep me away from Channel 3 for an extended period of time. And my entire focus has to be on getting better to come back and be with all of you and all of you here at Channel 3."
Donovan joined WKYC-TV in 1985 and became its sports director a year later. He has been the radio play-by-play voice of the Browns since 1999.
"On behalf of everyone here at the Cleveland Browns, I'd like to wish Jim a speedy recovery," Browns President Mike Holmgren said in a statement. "Jim has been a respected voice in the Cleveland sports scene for many years, and his association with our organization is held in high esteem. His name has become synonymous with the Browns and we consider him a part of our family. Our thoughts and prayers are with him and his family during this process."
Donovan said weekend sports anchor Dave Chudowsky will fill in for him at WKYC-TV during his absence.