David Livingston/Getty Images Since going public with stage III non-Hodgkin lymphoma in November 2024, Dave Coulier has been candid about his illness, treatment and prognosis before his second diagnosis. Non-Hodgkin lymphoma is a type of cancer that affects the patient's lymphatic system, with "white blood cells called lymphocytes [that] grow abnormally and can form growths (tumors) throughout the body," according to the Mayo Clinic. With his wife Melissa Bring by his side, Coulier has relied on his doctors' "very specific plan for how they were going to treat" the cancer.