The 2nd of May is the Feast Day of St. Peregrine Laziosi, Confessor, in the [traditional] Calendar proper to the Servite Order. It ranks as a Double of the Second Class and has a proper Office.
This is the day we ought to pray to St. Peregrine for all our kinsmen and kinswomen who are afflicted with cancer.
Here is a rough translation of the Collect as found in the Servite Breviary:
O God, Who didst marvelously grant unto blessed Peregrine an Angel for a companion, the Mother of God for teacher, and Jesus as the Physician unto [the healing of] a foul ulcer: grant by his merits, we implore, that we may singularly love [our] holy Angel [Guardian], the Virgin and the Savior upon the earth, and praise them in the heavens. Through the same our Lord Jesus Christ, Thy Son, Who together with Thee doth live and reign in the unity of the Holy Ghost, God, throughout all ages of ages. Amen.