Michael Douglas says his tumor is gone and that he believes it is likely he has beaten throat cancer.
"The odds are, with the tumor gone and what I know about this particular type of cancer, that I've got it beat," Douglas, 66, said in interview with NBC.
The Oscar-winning actor said he has been working on trying to regain the 32 pounds he lost during treatment.
"I'm eating like a pig ... and I've put about 12 back," he said.
Throat cancer can be a devastating illness -- hard to diagnose, hard to treat and especially hard on the body, with the possibility of losing the voice and even the ability to eat, but doctors had said all along that Douglas seemed to have a positive prognosis.
On David Letterman's "Late Show" in September, the actor said his doctors told him he had an 80 percent survival rate from a stage four cancer.
"He is being treated at Manhattan's Memorial Sloan-Kettering Cancer Center," the actor's press representative Allen Burry told ABCNews.com. "The tumor is at the base of his tongue and his doctor's prognosis is for a full recovery."
Doctors say that the optimistic prognosis is rare in throat cancer. If the cancer is associated with smoking and drinking, as the actor suggested his was, survival is usually around 60 percent, but only if caught in earlier stages.
"Mr. Douglas is very curable," said Dr. Kevin Cullen, director of the University of Maryland Greenebaum Cancer Center and a medical oncologist who specializes in head and neck cancer.
The actor told Letterman he had just finished his first week of radiation and chemotherapy after doctors had diagnosed stage four cancer, which Douglas called "very intense." The actor said he had been diagnosed three weeks earlier with cancer above the neck, although the first symptoms of a sore throat appeared earlier this year.
"Typically cancers of the tongue we treat with chemotherapy and radiation. The two are given at the same time," Cullen said.
"Together, it has proven to give a good chance for a cure for the disease," Cullen said. "But it is important to know if it is HPV-related, because those are the cancers that respond well to chemotherapy and radiation and have an excellent prognosis. The ones associated with smoking and drinking respond well, but not as well."
Survival rates for smoking and drinking-related throat cancers are around 50 percent to 60 percent and "the numbers go down from there," according to Cullen.
Those for HPV-related cancers are "higher than 80 percent," he said.
Douglas has said that he had a "walnut-sized" tumor at the base of his tongue.
Treatment is "manageable," Cullen said. "People get a sore throat and difficulty swallowing and they can also have irritation of the skin and throat from the radiation. But those things get better rapidly after treatment. Over a few months, he would hope to be eating normal food and after six months or more, we usually see someone who looks like they never had an illness."
Three months after treatment, the patient is evaluated to see if the disease is gone. There is a small risk of getting a second primary cancer "down the road," he said.
The worst survival rate is in the hypopharynx, which is a part of the throat area that is involved in the upper digestive tract. There are also three different subsites in the larynx.