In a taped interview with NBC's Matt Lauer, Douglas said he felt relieved after a "wild, six-month ride." Excerpts of the interview were released Monday ahead of its airing Tuesday on "Today."
Douglas says the odds are that he has beaten the disease.
He said that he had lost 32 pounds, but was now working out and had put 12 pounds back on. He said he'll continue to go in for monthly checkups.
On "The Early Show," Dr. Holly Phillips said Douglas's apparent recovery is "not entirely unheard of."
She said, "It still should be viewed as a huge, huge victory. He has every reason to feel victorious and to feel confident. But we also have to keep in mind, he'll need to be followed very closely especially for the next two years when the cancer is most likely to come back."
Phillips added people who've had throat cancer are also at an increased risk of getting other cancers of the head and neck.
Going forward, Phillips said Douglas will have to focus on building back his body.
"He's been through chemotherapy and radiation, both of which he described as very, very intense. Now, chemotherapy causes weight loss, and we've seen some recent photos of him actually where he looked quite gaunt. He says he's lost 32 pounds. He says he's lost a lot of muscle mass. So for the next few months, he'll really need to focus on building that back. And radiation can also cause some more long-term side effects, so we hope those like dry mouth and hoarseness will resolve over time."
She continued,"He's really going to need to eat right. He's going to need to exercise. Follow up with his doctor. The American Cancer Society actually recommends a primarily plant-based diet, focusing on fruits, veggies, lean protein like fish and beans. He can put that right back on. Now, some of the radiation side effects, particularly the dry mouth, the hoarseness, the throat discomfort, may be more lasting. There might even be some permanent side effects. But only time will tell to see how much he can recover from that."
Phillips said Douglas's consistent fighter outlook on the cancer helped him beat it "100 percent."
"Really, how you go into it is what you get out of it," she said. "He was determined to beat this. And from the looks of it today, he did. Now there will also be an emotional recovery, where he'll really have to focus on just building himself back, building his family back. But he's a survivor and he's shown that."
"Early Show" co-anchor Chris Wragge noted a three-year period must pass to really be considered cancer-free.
Phillips said, "Absolutely."
To avoid other cancers, Phillips said Douglas will have to avoid smoking and drinking.
"Throat cancer, eight out of 10 people who get throat cancer actually are smokers," she said. "Now, if you drink alcohol on top of that, your risk for the cancer increases exponentially. ... Other things that we can do is to try to avoid HPV. Now that is a sexually transmitted disease called human papilloma virus and it may be involved in about a quarter of all throat cancers. But also, we have to not just focus on prevention, but early detection. If you suddenly feel that something is caught in your throat, you're constantly clearing your throat, you experience any throat pain, ear discomfort, those are all signs you should tell your doctor. Not something to ignore and just try to tough it out."
The 66-year-old actor is set to begin shooting Steven Soderbergh's "Liberace" in May or June, with Douglas playing the title part. He's also nominated for a Golden Globe for his performance in "Wall Street: Money Never Sleeps.