The stage of a cancer tells you how big it is and whether it has spread. With cancer of unknown primary, the cancer has already spread. The type tells which type of cell the cancer started from.
There is no staging system for cancer of unknown primary (CUP). This is because the cancer has already spread. Find out why doctors can't accurately stage this cancer type.
Cancer of unknown primary can be grouped according to the type of cell they start from. Doctors can find out which type of cell the cancer started in by looking at a sample of the tumour under a microscope.
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