Once cancer is identified it is often further categorized with a grade and a stage. The grade of the cancer is based on how it looks microscopically. Grade is equivalent to aggressiveness. A cancer that has very few abnormal cells would be a lower grade than a cancer that appears very bizarre. Generally, the higher the grade, the worse the prognosis because a high grade cancer is often a very aggressive cancer that will spread.
Stage refers to the spread of the cancer.
This is important to know because it helps determine prognosis as well as treatment options. This is a process where cells break off from the cancer and travel through the blood stream or lymph, then lodge and grow in other parts of the body. Common sites of metastasis are the lymph nodes, liver, spleen, kidneys and lungs because these are organs that either filter the blood or have a very high volume blood supply. A low stage cancer means it hasn't spread and therefore has a better prognosis. A high stage cancer means it has spread and affected other organs.