Not sure I believe that prayer works, but he obviously did.
Saint Peregrine was born in 1260 in Forli, a town in Romagna, which is a region in Italy. His family was moderately wealthy, and as a young man, Peregrine was involved in politics. The city of Forli belonged to the anti-papal party in Italian politics. His father belonged to this party, but his mother was a pro-papacy believer. During a period of civil unrest, the pope sent Saint Philip Benizi to Forli act as a mediator. Peregrine, apparently ever the holder of strong opinions, struck Saint Philip Benizi in the face. Saint Philip Benizi responded by turning the other cheek, and praying for the youth Peregrine. This had an immense impact on Peregrine, who eventually repented and began to reform his life. Legend says that in penance for his early life's mistakes, he swore neither to speak nor to sit unless necessary to ministery. It is said that he spent nearly thirty years of his life on his feet! He spent great amounts of time in prayer, and developed a special devotion to the Blessed Mother. A vision of Our Lady inspired Peregrine to travel to Sienna and join the Servite Order, the same Order to which Saint Philip Benizi belonged. During the time he spent in Sienna, he became a priest, and was fervent in celebrating the liturgy and ministering to the people. He returned to Forli to found a new house for the Order, upon the orders of his superiors. It was while he was working on this project, that Saint Peregrine contracted a cancer of the foot, which caused him both excruciating pain as well as rejection by others due to its unpleasant appearance. He bore these burdens for some time, as the cancer resisted all treatments. At last the physicians decided that the only thing to do was to amputate the foot. Saint Peregrine spent the night before the operation in prayer, entrusting his fate to God. Toward morning, he fell into a light sleep, and dreamed that Christ Himself came from the cross and touched his leg, and awoke completely cured; the doctors could find no remaining trace of cancer. Saint Peregrine lived to the age of 85, dying in 1345. He was canonized in 1726.