Understanding kidney cancer

‘Cancer’ is not an all-inclusive or singular term. For each location in the body where cancer can occur, whether lung, skin, kidney or elsewhere, there are differences in disease characteristics, and how it can be treated.

Kidney cancer is a unique type of cancer with distinctive characteristics. Detection of kidney cancer is difficult because there are often no obvious signs or symptoms until a tumour may be quite large. Many of the symptoms that might occur – palpable mass, flank pain, or blood in the urine – may become manifest only when the cancer has grown to a large size. These considerations may lead to important delays in diagnosing kidney cancer, which may in turn lead to more advanced disease stage at diagnosis and may undermine treatment efficacy.

Fortunately, the majority of patients with kidney cancer do not belong to this category of patients. Most patients are diagnosed with incidental kidney cancer. This form of kidney cancer is discovered when the individual is being tested for something completely different, by ultrasound, CT scan, or another type of test.

The terms ‘kidney cancer’ and ‘renal cell carcinoma’ are often used interchangeably, but in fact renal cell carcinoma is the most common type of kidney cancer. Renal cell carcinoma includes several types of kidney cancer that are classified according to their appearance under the microscope, which is termed “histological type”. The three most common are the clear cellchromophobe and papillary types. Renal cell carcinoma is also classified according to its extent or stage.

A type of cell that looks clear inside when viewed under a microscope. Clear cell renal cell carcinoma is the most common type of kidney cancer. Approximately 75–80% of kidney cancers are this subtype.

Papillary renal cell carcinoma is the second most common type of kidney cancer. Approximately 10–15% of kidney cancers are this subtype.

Chromophobe renal cell carcinoma accounts for only 5% of all kidney cancers. Chromophobe kidney cancer rarely spreads outside of the kidneys.

Collecting duct carcinoma is a rare type of kidney cancer that arises in the collecting ducts of the kidneys.