Stage 4 cancer, also known as metastatic cancer, is the most advanced stage of cancer. At this stage, the cancer has spread from its original site to other parts of the body, such as lungs, liver, or bones. This spread can make treatment more complex and often indicates a more serious prognosis. Treatment options for stage 4 cancer may include chemotherapy, radiation therapy, or targeted therapies, depending on the type of cancer and its location. While stage 4 cancer is challenging to treat, some patients may experience periods of remission or improved quality of life through various therapies and supportive care.