EXCLUSIVE: Former President Jimmy Carter says he's not cancer-free: 'I'm still taking treatments'

Jimmy Carter says his body is responding well to treatments, but the former U.S. President says he's not entirely free from cancer.

Speaking exclusively with ET's Brooke Anderson in Plains, Georgia, Carter opened up about the struggle he still faces.

"They haven't detected any cancer, but sometimes the cancer spots [return]," Carter said, "including in my brain."

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So while Carter is doing well in his fight against the illness, he's still "taking treatments regularly."

"I'll continue that until the doctors tell me I don't have to anymore," said the 91-year retired politician, adding, "My immune system seems to be responding positively."

See photos of the former president through the years:

Carter, who has been a huge inspiration for others battling cancer, opened up about the inspiration he's gotten from his wife, Rosalynn Carter.

"Her support has helped me the last 69 years that we've been married, in everything I've tried," Carter shared. "Of course when I was ill, they thought I might die any time, and she was there for me. She grieved with me and was excited with me when I found out that my metabolism responded well to the treatment."

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In December, Carter announced that his brain cancer was gone, and that an MRI showed no signs of cancer at all. It seems that the announcement may have been premature, but the former president shows no signs of backing down in his battle against cancer.

For more on Carter's long fight against brain cancer, watch the video below.