Former Buffalo Bills quarterback Jim Kelly's oral cancer has returned. Kelly said in a statement Thursday morning that his family is once again asking for prayers.

Kelly released the following statement:

"As our family has faced many trials and triumphs throughout the years, you have blessed us with your prayers. We are asking for those prayers once again.  The oral cancer we hoped would be gone forever has returned. Although I was shocked and deeply saddened to receive this news, I know that God is with me. I continuously talk about the four F's. Faith, Family, Friends and Fans. With all of you by my side, we will fight and win this battle together. Staying "Kelly Tough" and trusting God, will carry us through this difficult time."

Kelly, who is in his late 50s, had jaw and sinus cancer and underwent months of treatment and surgeries.  He was declared cancer-free in 2014.  He's been receiving regular screenings since then.

Kelly appeared in four Super Bowls with the Bills in the early '90s and was selected to five Pro Bowls. He was inducted into the Pro Football Hall of Fame in 2002.