Grading is a way of classifying cancer of unknown primary (CUP) cells based on their appearance and behaviour when viewed under a microscope. To find out the grade of a tumour, the biopsy sample is examined under a microscope. A grade is given based on how the cancer cells look and behave compared with normal cells (differentiation).
With cancer of unknown primary (CUP), the doctor (pathologist) will try to identify the type of cell the cancer developed from (histology). The most frequently occurring CUPs are:
Identifying the cell type plays an important part in planning treatment for CUP. It can also be used to help judge a person's prognosis (future outcome).