Grade
The grade of a cancer is determined by a pathologist after the tumor has been surgically removed. The grade refers to how healthy or unhealthy the cancer cells look under a microscope. In other words, the grade of cancer is determined by comparing the amount of the healthy-looking tissue to the amount of cancerous tissue. If most of the tumor cells look like normal tissue, then the cancer is “well-differentiated” or “low-grade.” However, if the tumor cells look very different from normal tissue, then the cancer is “poorly-differentiated”, “undifferentiated”, or “high-grade.” The grade of the cancer may help to predict how quickly the cancer is likely to spread. All anaplastic thyroid cancers are undifferentiated and considered to be high grade.