Before your doctors can discuss treatment options with you they need to know how far your cancer has progressed and how quickly the cancer is growing or spreading. This is called staging and grading.
Staging is used to describe how big a cancer is and how far it has already spread. Information from the tests and scans used to diagnose your cancer is used to determine the stage of your disease.
The TNM system is a common system used for staging tumours:
T (tumour) plus a number indicates the size of the primary tumour and how far it has grown. The number refers to the stages described below:
T0 – there is no evidence of primary tumour in the kidney
T1 – the tumour is less than 7 cm in size and is completely contained within the kidney
T1a is a tumour less than 4 cm in size
T1b is a tumour between 4 and 7 cm in size
T2 – the tumour is more than 7 cm in size and is completely contained within the kidney
T2a is a tumour more than 7 cm but less than 10 cm in size
T2b is a tumour more than 10 cm in size
T3 – the cancer has spread beyond the kidney to the tissues or organs around the kidney, for example a major vein or the adrenal gland
T3a is a tumour that has grown into the renal vein or the fat surrounding the kidney
T3b is a tumour that has grown into the part of the vena cava (a large vein in the body), which is below the diaphragm
T3c is a tumour that has grown into the part of the vena cava, which is above the diaphragm, and it is growing into the wall of the vena cava
T4 – the cancer has spread beyond the tissues or organs around the kidney to more distant organs in the body
N (nodes) plus a number indicates that the cancer has spread to nearby lymph nodes. The number refers to the number of affected lymph nodes:
N0 – cancer has not been detected in any lymph nodes
N1 – cancer has spread to one nearby lymph node only
N2 – cancer has spread to more than one nearby lymph node
M (metastases) plus a number refers to places elsewhere in the body where the cancer has spread. M0 means there are no distant metastases and M1 means distant metastases are present.
Your doctor will combine these figures to give an overall staging, e.g. T2 N0 M0, which means the cancer is bigger than 7cm but still confined to the kidney, there is no involvement of lymph nodes and there are no metastases.
Another staging classification, which is sometimes used for kidney cancer, is a number system; the cancer is simply said to be stage 1, 2, 3 or 4 (or stage I, II, III, or IV). Again, the stages reflect how large the primary tumour has become, and whether the cancer has spread to lymph nodes or other areas of the body. A stage 4 tumour is often referred to as an advanced cancer. The number system used for kidney cancer is as follows;
- Stage 1 – the cancer is confined to the kidney and is less than 7cm in size
- Stage 2 – the cancer is bigger than 7cm but still confined to the kidney
- Stage 3 – the cancer has started to spread outside the kidney to the adrenal gland or a major vein nearby. The cancer may have spread to no more than one nearby lymph node.
- Stage 4 – the cancer has spread to nearby tissues or organs and more than one nearby lymph node contains cancer cells OR the cancer has spread to other parts of the body further away.
Finding the stage of a cancer helps doctors to advise on what is the best treatment and gives them a reasonable indication of the outlook (prognosis). It also describes the cancer in a standard language which is useful when doctors discuss patients, and when patients are involved in clinical trials. When discussing your treatment options, your doctor will also take into account how well you are overall.
Doctors grade cancers to indicate how quickly or slowly a cancer is likely to grow and spread. Cells from a sample of the cancer (a biopsy) are looked at under the microscope or tested in other ways. By looking at certain features of the cells the cancer can be graded as low, intermediate or high grade; this system is called the Fuhrman system:
- Grade 1 or low-grade cells are usually slow-growing, look quite similar to normal cells, tend to be less aggressive and are less likely to spread.
- Grade 2 or intermediate grade cells grow more quickly, look abnormal, are moderately aggressive and could spread.
- Grade 3 or high-grade cells are likely to grow more quickly, look very abnormal, tend to be more aggressive and are more likely to spread.
- Grade 4 or high-grade cells look very abnormal, grow very quickly, are extremely aggressive and are very likely to spread.
Biopsies are usually taken during surgery to remove the affected kidney and are also used to determine the type of kidney cancer a patient has, for example, clear cell or papillary.