Specter, 82, announced Aug. 28 that he was battling non-Hodgkin's lymphoma, the Philadelphia Inquirer reported.
He was released from the hospital Friday, but is expected to return to the hospital occasionally for additional treatment, officials said.
Specter underwent treatment for brain tumors in 1993 and 1996. He also had heart bypass surgery in 1998.
2014: The Year in Music [PHOTOS]