Former U.S. President Jimmy Carter revealed on Thursday that melanoma has spread to his brain. The 90-year-old will undergo radiation treatment for three weeks, starting on Thursday afternoon.The president described the cancer, which was found during a liver operation this summer, as "very small spots," approximately two millimeters in size."I've had a wonderful life. I've had thousands of friends. I've had an exciting and adventurous and gratifying existence," Carter said on Thursday during a press conference. "It's in the hands of God [...] I'm ready for anything." "It's in the hands of God [...] I'm ready for anything.