Kelly announced last month that his cancer had returned and that doctors decided surgery to treat it wasn't the best option.
He's scheduled to undergo chemotherapy and radiation treatments, and says he has good and bad days.
"I am getting better," he said.
"My big battle is Monday when I go in to start my radiation and chemo," Kelly told MSG. "I hope when it's all over they get everything, but right now we're praying for a miracle."
"Kelly's condition remains very treatable and potentially curable," Dr. Peter Costantino, executive director of Lenox Hill's New York Head & Neck Institute, said in a statement Tuesday. "Even if chemotherapy and radiation are not successful in eradicating the cancer, his skull-base tumor remains operable."