The senator said his disease is actually less advanced than it was in 2005 when he was successfully treated, The Philadelphia Inquirer reported. He told reporters he expects to continue to function as a senator during three months of chemotherapy.
"I consider this just another bump on the road to a successful recovery from Hodgkin's, from which I've been symptom free for three years," he said.
The 78-year-old is running for a sixth term.
His recent book, "Never Give In," described his experience with cancer. In addition to the Hodgkin's, he was treated 15 years ago for a brain tumor, which recurred three years later, and has had to deal with heart bypass surgery and cardiac arrest.
The five-term senator is one of the few moderate Republicans remaining. He is the ranking Republican on the Judiciary Committee and served as its chairman until the Democratic takeover of Congress in 2006.