Kidney Cancer is not just one disease. There are a number of different cell types, each of which responds somewhat differently to treatment.
- can come from different cells of the kidney and thus have different “flavours” or “sub-types” of cancer (for further information read “histology”)
- can be more slow-growing or more aggressive (“grade”)
- can be larger or smaller, or have spread outside the kidney (“stage”).
All of these factors can affect:
- How aggressive the tumour is and how likely it is to spread.
- Which treatment(s) (if any) you should have.
- Which clinical trials you could take part in.
Kidney cancer can be sub-divided into several different “flavours” or “sub-types” based on the appearance of the cancer cells under a microscope (the “histology” of the cancer). The type of kidney cancer is not usually important for surgery, but can be critical if more treatment is needed later.
The most common histologies are:
- Clear cell carcinoma: The most common form of kidney cancer, accounting for about 75% of people with renal cell carcinoma.
- Papillary cell carcinoma: About 10% to 15% of people have this form of kidney cancer.
- Chromophobe carcinoma: Accounts for about 5% of cases.
- Other rare types: About 5% of people have other rare forms of kidney cancer
To find out what type of kidney cancer you have, please refer to your Pathology Report or ask your doctor.
Each patient’s tumour is different from other peoples‘ cancers in how aggressive it looks; the “grade” of the tumour. The grade of a cancer describes if the cells in the cancer are almost uniform and well organised, almost like a normal organ or tissue might look under the microscope (low grade), or if the cancer looks very disorganised and the cells are different in size and shape (high grade).
The stage of a cancer describes the size of the cancer, and whether or not it has spread. This helps to guide treatment and can help plan long-term follow-up care. When staging is based on clinical assessment alone, it is referred to as the clinical stage. Microscopic examination of the affected tissue determines the “pathologic” stage. A staging system is a standardised way in which the cancer care team describes the extent of the cancer.
Your doctor will determine the “stage” of your kidney cancer based on:
- The size of the tumour (“T-stage”)
- Spread of the cancer to the nearby lymph nodes (“N-stage”).
- Spread of the cancer to other organs (“M-stage”) e.g. metastasis to liver, lung or bone.
The four main stages of kidney cancer are based on this TNM staging system, which is one of the methods for “staging” kidney cancer.While clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer, there are several other important cell types as well:
- Clear cell = 75%
- Papillary type I = 5%
- Papillary type II = 10%
- Chromophobe = 5%
- Oncocytoma = 5%
In each case, a different genetic alteration is present, which changes the chemical processing in the cell and makes it more or less responsive to the action of each of the drugs on the market. Thus the genetic analysis of the tumor tissue may be important in choosing the right drug.