There are multiple descriptions we use to characterize a cancer. The most important characteristics are: the tissue it arises from, the stage and the grade (on tumor stage see blog: What Is Tumor Stage). The grade tells us how abnormal the cancer cells look under the microscope; in other words, how different the cells are from the cells of the original normal tissue. Cancers that look more normal are low grade and cancers that look very abnormal are called high grade. Low grade cancers are well differentiated, whereas high grade cancers are poorly differentiated or undifferentiated. Grade corresponds with how aggressive the disease is. Low grade tumors grow and spread slower, while high grade tumors grow and spread rapidly. Doctors use tumor grade, along with stage and some other factors (age, performance status) to determine prognosis and to develop a treatment plan. Lower grade cancers typically have better prognoses and sometimes treatment can be delayed or even foregone, whereas high grade cancers need more aggressive approach and closer monitoring.
Peter Acs, MD, PhD – Medical Oncologist
Updated 11:00 AM ET, Sunday April 29, 2018