A 1992 article in the trade magazine Media Industry News about the launch of the magazine Cigar Aficionado said Gumbel was among a group of "celebrity smokers" the magazine might profile.
The magazine did not respond to a request for comment, but a search of its archives did not reveal any articles about possible tobacco use by Gumbel in the time since its launch.
"Lung cancer has a high risk of relapse," said Dr. Lucas Wong, an oncologist at Scott & White Healthcare in Temple, Texas.
And smoking plays a major role in the possibility of such a relapse.
"The important thing is, if he was a smoker, that he stop smoking," said Brooks.
He noted that prognosis for lung cancer caught in the early stages tends to be much better, a fact that has led to more emphasis on developing ways to catch cancers sooner.
"We are constantly trying to find ways to detect cancer in an earlier stage," said Brooks, noting recent study in ways, such as blood tests, that doctors are trying to find markers for lung cancer.
With the information that is available, there is only so much that can be determined about Gumbel's outlook. But the bottom line, said Brooks, is that the positive face Gumbel presented on "Regis and Kelly" is probably warranted.
"The good news is he's had surgery, it sounds as though the cancer has been removed, and he looks healthy enough to do a TV, show, which is a good sign," he said.
ABC News information specialist Nicholas Tucker contributed to this story.