Tonawanda News — Receiver Andre Reed, Kelly's favorite target, called the quarterback a "tough dude."
"Jim's a fighter. We think he'll be OK. We're all in his corner," Reed said. "He's such a resilient guy, and that's been our motto forever, in whatever we did.
"He's got the support, and Jim will be OK."
Kelly spent 11 seasons with the Bills before retiring following the 1996 campaign, and has since made Buffalo his home. Known for his fearless, swashbuckling style, Kelly was the face of Bills teams that made four consecutive Super Bowl appearances in the early 1990s, only to lose them all.
Inducted into the Pro Football Hall of Fame in 2002, Kelly still holds nearly every significant career franchise passing record — 35,467 yards, 237 touchdowns and 26 300-yard games.
News of Kelly's condition also attracted many well-wishers from around the world on social media. The term, "PrayersForJK," became popular on Twitter.
"I LOVE JIM KELLY," Kelly's teammate and Hall of Fame running back Thurman Thomas posted on his Twitter account.
The diagnosis stems from pain Kelly began experiencing in his jaw in December. He initially thought it was an infection, but grew concerned when antibiotics failed to help.
Tests eventually led to doctors removing a nickel-sized cyst from his gums and nasal cavity during an operation in early March. Follow-up tests revealed the cancer.
"When you hear the word 'cancer,' it automatically scares you," he said. "But I'm very confident. My faith is definitely there. And that probably, more than anything, has kept me going, and the support I've gotten from my family."
Concerns about the 53-year-old's health were first raised last week when his wife, Jill Kelly, posted a message published on imgur.com. Without going into detail, Jill Kelly noted that the family was going through a "more serious battle under our roof," and asked followers to pray for her husband "for healing."