John Piper has prostate cancer. He has published a letter about it on his website
He asks for prayer as follows: All things considered, Noël and I believe that I should pursue the treatment called radical prostatectomy, which means the surgical removal of the prostate. We would ask you to pray that the surgery be completely successful in the removal of all cancer and freedom from possible side effects.
His own prayer is: So I am praying: “Lord, for your great glory, 1) don’t let me miss any of the sanctifying blessings that you have for me in this experience; 2) don’t let the people of Bethlehem miss any of the sanctifying blessings that you have for us in this; 3) grant that the surgery be successful in removing cancer and sparing important nerves; 4) grant that this light and momentary trial would work to spread a passion for you supremacy for the joy of all peoples through Jesus Christ; 5) may Noël and all close to me be given great peace—and all of this through the grace of our Lord Jesus Christ, to whom be glory for ever and ever, Amen.” I hope God will lead you to pray in a similar way.