Kelly underwent surgery last June to remove cancerous cells in his jaw. At the time, chemotherapy and radiation treatment were not necessary.
Erie County Medical Center, the Buffalo hospital treating Kelly, released a statement to WGRZ saying, "Jim Kelly came to ECMC this week for continued testing related to his oral surgery. Unfortunately, it has been determined that his cancer has returned. Our team of head and neck cancer specialists is determining a course of treatment that will allow Mr. Kelly to battle this cancer successfully. Mr. Kelly has asked that you keep him and his family in your thoughts and prayers."
Kelly, who played from the Bills from 1986 to 1996, was inducted into the Pro Football Hall of Fame in 2002. He holds nearly all of the franchise's passing records.