When solid tumors are diagnosed, they are often assigned a grade and a stage. The grade of a tumor — the cancer grade — is an indication of how quickly it is likely to grow and spread. In general, low-grade tumors grow slowly and higher-grade tumors grow more rapidly. Tumors are assigned a grade based on the appearance of their cells under a microscope: Low-grade tumor cells resemble normal cells more closely than high-grade tumor cells do.
The stage of a solid tumor refers to its size or extent and whether or not it has spread to other organs and tissues. The actual number used to describe a tumor stage – 0, 1, 2, 3, or 4 – can have a different meaning for different types of cancer, but, in general, the higher the number, the more advanced the disease is. Oncologists use staging to arrive at a prognosis of the disease and help choose the best treatment.
The American Joint Committee on Cancer, which develops systems for classifying cancer, uses three criteria for staging solid tumors: the extent of the tumor (designated T), the presence or absence of tumor cells in the lymph nodes (N), and the presence or absence of metastasis (M).
If you have been diagnosed with cancer, talk with your doctor about its grade, stage, and other matters.