Cancer stage 4 is also known as metastatic cancer because it has spread to distant parts of the body from its original site. Stage 4 cancer is the most critical stage and a cure is generally not possible. The approach to treating stage 4 cancer often aims to improve quality of life and reduce symptoms and pain that may arise. Despite suffering from stage 4 cancer, there is a possibility that someone can survive for several years.

"T" for tumor is used to measure the size and location of abnormal tissue growth. "N" referring to lymph nodes is used to determine whether cancer cells have spread to the lymph nodes, which are a vital part of the immune system that carries white blood cells to help fight infection. "M" representing metastasis is used to assess whether cancer cells have spread to other parts of the body.

Cancer spreads through early growth in surrounding tissue, then spreads through the lymph nodes or blood vessels. From there, cancer cells can spread through the lymphatic system or bloodstream to distant parts of the body, causing metastasis and reaching stage 4 cancer. The medical team will assess the cancer tumor to determine its stage from 0 to 4. This assessment is important in planning treatment and estimating prognosis.

The stages of cancer include: Stage 0, known as carcinoma in situ, where abnormal cells have not yet spread. Stage 1 indicates the presence of cancer that has not spread to surrounding tissues. Stage 2 indicates the presence of cancer that has invaded surrounding tissues and may have spread to lymph nodes. Stage 3 describes cancer that has grown into surrounding tissues and may have spread to lymph nodes. Stage 4 indicates that cancer has spread to distant parts of the body.

Diagnostic tests for stage 4 cancer include: Blood tests: Complete blood count (CBC) is useful for measuring the number of blood cells and searching for signs of tumors to detect the presence of cancer cells and other indications. Biopsy: The process of taking tissue samples which are then sent to the laboratory to search for cancer cells. Endoscopy: The use of a thin tube to view organs inside the body. X-ray: An imaging method used to view bone structure or internal organs.

Chemotherapy is the main method in the treatment of stage 4 cancer using drugs to eliminate rapidly developing cancer cells. Radiation therapy is recommended by the medical team to shrink tumors that cause pain or other disruptive symptoms. Targeted therapy uses drugs that target specific proteins or genetic mutations to inhibit cancer growth.