What grade is assigned to tumors that are poorly differentiated?

Tumors that are poorly differentiated are assigned a grade of G3. This grading system evaluates how much the tumor cells differ from normal cells, which gives insight into the tumor's aggressiveness and potential behavior. Poorly differentiated tumors typically have a more chaotic structure and do not resemble the normal tissue from which they arise. This lack of differentiation is associated with a higher likelihood of aggressive behavior, increased growth rate, and a poorer prognosis.

In the grading system, G1 indicates well-differentiated tumors, which closely resemble normal tissues and generally have a better prognosis. G2 refers to moderately differentiated tumors, showing some abnormal characteristics, but not as severe as G3. G4 tumors are considered undifferentiated, where the cancerous cells do not maintain distinct characteristics of any particular tissue type. However, G3 is specifically designated for those tumors that are poorly differentiated but still retain some identifiable features, marking them as aggressive yet not entirely uncharacteristic. This grading helps healthcare providers in making treatment decisions and prognostic assessments for the patient.