Knowing the stage and grade of a cancer helps your doctor decide about the best treatment for you.
What staging means
The stage of a sarcoma tells the doctor how big it is and whether it has spread. The tests and scans you have when diagnosing your cancer give some information about the stage. It is important because treatment is often decided according to the stage of a cancer.
There are different ways of staging cancers. The two main ways are the TNM system and number systems.
Generally speaking, the lower the stage, the more chance of curing the cancer. Doctors also take the grade of the cancer into account when staging sarcomas.
Grades of soft tissue sarcomas
Grade is important because it tells you how the cancer is likely to behave. A low grade cancer is likely to be slower growing and less likely to spread to another part of the body. A high grade cancer is likely to be faster growing and is more likely to spread than a low grade sarcoma.
The grade is one of the things your doctors need to know to work out the stage of your sarcoma.
Your doctor takes a sample of the sarcoma (a biopsy). A pathologist looks at the sample under a microscope to grade it. The grade is based on 3 factors. These are:
- differentiation - the pathologist scores the cancer cells from 1 to 3, 1 meaning that the cells look very similar to normal cells, 2 meaning that the cells look more abnormal than low grade cells and 3 meaning they look very abnormal
- mitotic count - the pathologist looks at how many cells are dividing under the microscope and scores from 1 to 3, a lower score meaning fewer cells are dividing
- necrosis - the pathologist looks at how much of the tumour is made up of dying tissue and gives a score from 0 to 2, a lower score meaning there is less dying tissue
How cancers are graded
The doctor adds together the score from each factor and grades the cancer as:
- grade 1 (G1), if there is a total score of 2 or 3
- grade 2 (G2), if there is a total score of 4 or 5
- grade 3 (G3), if there is a total score of 6 or more
Your doctor may describe your sarcoma as low grade (grade 1) or high grade (grade 2 or grade 3).
The TNM stages
TNM refers to tumour, nodes and metastasis. Metastasis means whether the cancer has spread to another part of the body.
There are 2 T stages for soft tissue sarcomas but each stage is divided into a and b:
- t1a means the tumour is 5cm or less across at its widest point, and is near the body surface (superficial)
- t1b means the tumour is 5cm or less across and is deep in the body tissues
- t2a means the tumour is more than 5cm across and is near the body surface (superficial)
- t2b means the tumour is more than 5cm across and is deep in the body tissues
There are 2 N stages:
- n0 means no lymph nodes have been found that contain cancer cells 9
- n1 means there are sarcoma cells in at least 1 lymph node
It is not common for soft tissue sarcomas to spread to lymph nodes.
There are 2 M stages:
- m0 means there are no signs that the sarcoma has spread to another part of the body
- m1 means that the sarcoma has spread to another part
The number stages
There are 4 major number stages for sarcomas. But stage 1 and stage 2 are both divided into 2 subgroups. The number stages of soft tissue sarcomas are:
- Stage 1A – the tumour is low grade, small (5cm or less), superficial or deep with no sign of spread
- Stage 1B – the tumour is low grade, large (more than 5cm) and superficial or deep with no sign of spread
- Stage 2A – the tumour is medium or high grade, small, superficial or deep with no sign of spread
- Stage 2B – the tumour is medium or high grade, large, superficial or deep with no sign of spread Stage 3 – the tumour is high grade, large, superficial or deep, or the tumour is any size or grade but has spread to lymph nodes
- Stage 4 – the tumour can be any size and any grade, but has spread to another part of the body including lymph nodes
Recurrence means a soft tissue sarcoma has come back after it was first treated.