Radiation is also used to treat inoperable tumors and
tumors that have spread to the brain from another part
of the body (metastatic brain tumors). Radiation may
also be used to prevent metastatic brain tumors from
developing. This type of preventative therapy is called
prophylactic radiation, and is most often used for people
with small-cell lung cancer. Sometimes the purpose of
radiation therapy is to relieve symptoms rather than to
eliminate the tumor. This is called palliative radiation