"I have a wonderful doctor and nurse, and everybody taking good care of me," he told Gayle King on "CBS This Morning". "I'm very hopeful and very optimistic."
In December, Lewis was diagnosed with Stage 4 pancreatic cancer following a routine medical visit.
"I have been in some kind of fight -- for freedom, equality, basic human rights -- for nearly my entire life. I have never faced a fight quite like the one I have now," he said at the time.
CNN has reached out to Lewis' office for additional details on his condition Thursday.
Lewis, who in March 1965 joined forces with Martin Luther King Jr. to lead a voting rights march out of Selma, Alabama, is in his 17th term as a member of Congress.
In his CBS interview, he discussed the growing unrest across the country following the death of George Floyd. "The way this young man died, watching the video, it made me so sad. It was so painful. It made me cry. I kept saying to myself, how many more? How many more young black men will be murdered? The madness must stop," he said.
When asked about President Donald Trump's threat of military intervention, Lewis replied, "I think it would be a serious mistake on the part of Trump to stop orderly peaceful nonviolent protests. You cannot stop the call of history." He drew from his own history, adding, "You may use troopers. You may fire hoses and water. There cannot be any turning back. The world is seeing what is happening. We are ready to continue to move forward."
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