Stage 4 cancer is cancer that has spread to distant sites within the body, according to the American Society of Clinical Oncology (ASCO). Stage 4 cancer is sometimes called metastatic cancer or advanced cancer, and it can be harder to treat than cancer diagnosed at earlier stages.
The stage at which cancer is diagnosed is used by the treatment team in predicting the prognosis of a patient, the patient's chance of recovering from the cancer and the treatment plan that is used. Staging is used to describe the location of cancer, if it has spread, where it has spread to and whether other organs are affected by it, notes ASCO.
Three factors usually determine staging for most cancers, including the tumor's growth and size, whether the lymph nodes have been reached and whether distant sites in the body have been reached. Grade, tumor genes and tumor markers are used along with staging to describe the cancer more fully.
Using staging, doctors can devise the most suitable treatment plan for cancers, including surgical goals or treatment regimens using radiation or chemotherapy. Staging can also be useful in predicting recurrence of cancer and the effectiveness of treatment. Staging allows the entire health care team and doctors from multiple facilities to communicate more effectively in regards to treatment of the patient.