Bryant Gumbel had surgery two months ago to remove a malignant tumor from his lung.
The former NBC News star and current HBO sports anchor made the announcement Dec. 8 on Live! with Regis and Kelly.
Gumbel, who was filling in for Philbin who is recovering from hip replacement surgery, told viewers that part of his lung was removed in the surgery.
"We had told a few people, we told my family, obviously," Gumbel said. "I even kept it from my staff at Real Sports. So I'm okay for the time being."