As more treatments known as immunotherapies for cancer emerge, here are some terms to know:

Immunotherapy: Forms of treatment that use or boost your own immune system to fight cancer.

T cells: White blood cells that fight disease by tracking and destroying certain infected or abnormal cells.

Checkpoint inhibitors: Immunotherapy drugs like the brand Keytruda used to treat former President Jimmy Carter. They block one path that tumors use to repel an immune attack.

Cellular immunotherapy: A type of immunotherapy using living immune cells that are collected from a patient, grown or modified in a...