Grading soft tissue sarcoma

Grading describes how the cancer cells look compared to normal, healthy cells. The grade gives your healthcare team an idea of how quickly the cancer is growing and how likely it is to spread. This helps them plan your treatment. The grade can also help the healthcare team predict future outcomes (your prognosis) and how the cancer might respond to treatment. The grade is also used to help stage soft tissue sarcoma.

To find out the grade of soft tissue sarcoma, a pathologist looks at a tissue sample from the tumour under a microscope. The factors used to determine the grade for soft tissue sarcoma include:

• how often the cells are dividing (mitotic index)
• the number of dead cells or tissues that are present (necrosis)
• the number and kinds of cells in a tissue sample (cellularity)
• the size and shape of cells and their nuclei( pleomorphism)
• the type of cancer (histologic type)
• how different the cells look from normal cells (differentiation)

The pathologist usually gives soft tissue sarcoma a grade from 1 to 3. A lower number means the cancer is a lower grade. There are several different grading systems used for soft tissue sarcoma and some of them have 2 or 4 grades instead of 3 grades.

Low-grade cancers have cancer cells that are well differentiated. The cells are abnormal but look a lot like normal cells and are arranged a lot like normal cells. Low-grade cancers tend to grow slowly and are less likely to spread.

High-grade cancers have cancer cells that are poorly differentiated or undifferentiated. The cells don’t look like normal cells and are arranged very differently. High-grade cancers tend to grow more quickly and are more likely to spread than low-grade cancers.