What are stage 4 cancer treatment options?

Palliative care: Stage 4 cancer, by definition, is not curable. It would depend on the clinical situation, patient choice and expected response to treatment, wether to pursue active treatment. Palliative and/or hospice care would be one consideration.

Depends: Depends on type, but most often some sort of chemotherapy is used. Today there are many new "targeted therapies" that turn off specific things in the cancer cells that make them grow that might be used instead of chemo. Some stage IV cancers are treated with immunotherapy. Surgery or radiation may be used to focus on problem spots that are resistant to the other treatments.