I think that this is the following John Joyce who was with the Canadian Medical Corps.
According to his attestation papers dated July 22, 1915 at Toronto, John Joyce was born on January 14, 1881 at Toronto. He listed his wife Louisa Joyce, 64 Austin Avenue, Toronto as his next of kin. He was a butcher and had no previous military experience. He was 34 years of age and stood 5 feet 8 inches in height. He had brown eyes and hair and a dark complexion. He was Roman Catholic.
He was a member of the "B" Division Wing, Canadian Medical Corps when he died on October 30, 1918 at No. 7 Canadian General Hospital, Etaples of pneumonia. He is buried in the Etaples Military Cemetery, France.