As of 2015, chemotherapy and biological, hormonal, radiation and targeted therapies are used to treat metastatic cancer, says the American Cancer Society. Surgery is also a treatment option, and different combinations of these approaches are used. The number, size and location of tumors, the type of cancer, and the patient's age and general medical condition determine a course of treatment.
A particular treatment is chosen based on where the cancer begins, according to the National Cancer Institute. For instance, prostate cancer that spreads, or metastasizes, is still treated as prostate cancer. Different types of cancers spread through the body in different ways. Cancer cells that break loose from a particular spot travel through the blood or the lymphatic system and sometimes get caught in a nearby organ or lymph node, where they begin to reproduce. Metastasis often occurs in the lungs, because blood from other areas of the body passes through the lungs' blood vessels.
Chemotherapy is applied intravenously or directly to the affected region, especially with metastatic liver cancer, says News Medical. Surgery is combined with chemotherapy to remove lung, bone and liver tumors. Hormonal therapy is used to treat cancer in the endocrine system, such as breast or prostate cancer. Radiation therapy is used to treat large metastatic cancers and those that make surgery problematic, such as brain and lung cancer. Other treatments include thermal ablation, which uses heat and cold, and biologic therapies that cut off the blood supply to cancer cells.