CANCER GRADING AND STAGING METHODS-LESSON 107
Tumors are classified on the basis of their location, microscopic appearance, and extent of spread. Of particular importance are the tumor's GRADE that is the degree of maturity or differentiation under the microscope and STAGE that is the extent of spread within the body. These two properties influence the prognosis that is the chances of successful treatment and survival and determine the specific treatment to be used. When grading a tumor, the pathologist is concerned with the microscopic appearance of the tumor cells, specifically with their degree of maturation or differentiation. Often, four grades are used. Grade I tumors are very well differentiated, so that they closely resemble the normal parent tissue of their origin. Grade IV tumors are so undifferentiated or anaplastic that even recognition of the tumor's tissue of origin may be difficult. Grade II and III are intermediate in appearance, moderately or poorly differentiated, as opposed to well differentiate...