With regard to liver cancer, "stage IV" refers to invasion of nearby lymph nodes, blood vessels and organs. Stage IV actually has two subcategories. Stage IVA liver cancer hasn't spread to remote parts of the body, while Stage IVB liver cancer has, according to Cancer Treatment Centers of America.
The American Joint Committe on Cancer devised the TNM system to describe the various stags of cancer. The stages are denoted by Roman numerals I through IV, and the higher the number, the more the cancer has spread. With most cancers, the staging system only relies on the degree to which the cancer has spread. With liver cancer, however, liver function is an additional factor with regard to options for treatment and general prognosis, according to the American Cancer Society.
When it comes to treating liver cancer, doctors frequently base their decisions on the possibility of surgical removal. A resectable tumor can be taken out via surgery, while cancer that could potentially be resolved by way of a liver transplant is called potentially transplantable, notes the American Cancer Society. In cases of stage IV cancer, though, the cancer has spread considerably beyond the scope of the liver, requiring a treatment plan tailored to the individual, explains Cancer Treatment Centers of America.