Determining the Grade of the Tumour

Pathologists will typically report on the grade of the tumour. This is a qualitative interpretation by the pathologist of how much the cancerous cells resemble normal tissue from that site. There are several different grading systems that might be used. The most common are as follows:

  • GX:Grade cannot be assessed
  • G1:Well differentiated
  • G2:Moderately differentiated
  • G3:Poorly differentiated
  • G4:Undifferentiated

Differentiation refers to how closely the cells taken from a tumour or lesion resemble normal cells from the healthy tissue surrounding the tumour. “Well differentiated” means that the cells look like normal cells in that area. “Undifferentiated” means the cells look nothing like normal cells in that area.

While it is important to report the tumour’s grade, few doctors use this information to make decisions regarding treatment or prognosis for this cancer type.