This is what I found on the web:
Stage IV: Many tumors spread throughout an organ such as the liver or stomach, as well as in the lymph nodes. Stage A measure of how far a cancer has spread throughout the body. Stages range from Stage I, which is a localized tumor that has not spread, to Stage IV, in which the cancer has spread to parts of the body far away from the original tumor. Stage I cancers have a better outlook than do Stage IV cancers. IV can also refer to a single tumor in another organ, plus tumors in distant lymph nodes.
They did not mention it above but stage IV may also mean that the disease has spread to the bone marrow.
All the best,
Kasia
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