Updated

Former Tennessee Republican Sen. Fred Thompson, who has been mulling a run for the White House, told FOX News on Wednesday he's in remission from indolent lymphoma.

“As you know, I’m thinking about running for president. There are certain things that you have to check off, in my mind, in order to do that,” Thompson said.

The "Law & Order" star said he was diagnosed with the disease in 2004 after a routine physical. He said the cancer is "fortunately a good kind if you can ever call something like that a good kind" and treatable.

"I have had no illness from it, or even any symptoms. My life expectancy should not be affected. I am in remission, and it is very treatable with drugs if treatment is needed in the future — and with no debilitating side effects," Thompson said in a personal commentary following the interview.

According to the American Cancer Society, this year doctors will diagnose about 63,000 new cases of indolent lymphoma, a slow-growing type of cancer that affects the lymphatic system, the part of the body that helps regulate the immune system.

Thompson has a favorable prognosis, said Dr. Bruce Cheson of Georgetown University Hospital. Thompson had been on a cancer therapy called Rituxan, but is not currently in treatment.

"Some lymphomas are very aggressive, but people with slow-growing types, like Senator Thompson's, often (die) from natural causes associated with old age, rather than from the disease," Cheson said.

The illness also appears to have no impact on Thompson's personal consideration of a White House bid.

"I wouldn't be doing this if I wasn't satisfied in my own mind as to the nature of it and the fact that not only will I have an average life span, but in the meantime, I will not be affected in any way by it," Thompson said. "Of course nobody knows the future but that has been in the history for almost three years now in terms of no symptoms and no sickness."

After much coaxing in conservative circles, Thompson, 64, told FOX News last month that he was contemplating a bid for president. The character actor who plays district attorney Arthur Branch on the long-running NBC drama said he began pondering a run after former Senate Majority Leader Howard Baker and other Tennessee Republicans began drumming up support for his possible Republican candidacy, citing his conservative credentials.

A former minority counsel in the Watergate hearings and a close friend of Arizona Sen. John McCain, another 2008 GOP White House hopeful, Thompson said releasing information about his health is necessary before announcing any campaign plans.

"The American people have a right to know this. And they have a right to voice their opinions whether they think it's a big deal or not. And I know it's not a big deal as far as my health is concerned, as much as a person can know things like that. But other people have a right to look at it and weigh in and I have a need to factor that into my decision in terms of the reaction I get of that," he said.

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