Who gets kidney cancer, where it starts and how common it is.
The kidney and urinary system
Kidneys are part of your urinary system. This system filters waste products out of the blood and makes urine. It includes:
- 2 kidneys
- 2 ureters
- prostate (in men)
The kidneys are two bean shaped organs, each about the same size as a fist. They are near the middle of your back, one on either side of your spine.
How the kidneys work
Inside the kidney tiny networks of tubes called nephrons filter the blood. As blood passes through the nephrons all unwanted waste is taken away. Chemicals that your body needs are kept or returned to the bloodstream.
Inside the nephrons waste products move from the small blood vessels into urine collecting tubes. The urine gathers in an area called the renal pelvis at the centre of each kidney. From here it drains down a tube called the ureter and into the bladder.
There are 2 ureters, one from each kidney. Another tube called the urethra carries the urine from the bladder out of the body.
The kidneys have a very rich blood supply. Blood passes through in large amounts so the kidneys can filter it and remove waste products.
The main blood vessel to the kidney is called the renal artery. There are also large blood vessels carrying the cleaned blood away. These are called the renal veins.
The kidneys also produce three important hormones:
- erythropoietin (EPO) which tells your bone marrow to make red blood cells
- renin, which regulates blood pressure
- calcitriol (a form of vitamin D) which helps the intestine absorb calcium to keep your bones healthy
Above each kidney is an adrenal gland. These small glands make:
- cortisol, a natural steroid hormone
- aldosterone, which helps to regulate the body’s water balance
- noradrenaline, an adrenaline like hormone
If you have a kidney removed, you may have the adrenal gland above it removed too. This happens when there is a chance that cancer cells could be left behind with your adrenal gland.
The adrenal hormones are important but:
- you will be perfectly well with only one adrenal gland – your other one will make all the hormones you need
- if you have both adrenal glands removed you need to take hormone tablets every day
Where it starts
The kidneys are made up of different types of cells. The type of cancer you have depends on the type of cell the cancer starts in.
The most common type of kidney cancer is renal cell cancer. It starts in the cells lining the tubules (the smallest tubes) inside the nephrons.
The main types of renal cell cancer are:
- clear cell - around 75 out of 100 renal cell cancers (75%)
- papillary - around 10 in 100 renal cell cancers (10%)
- chromophobe - around 5 in 100 renal cell cancers (5%)
Who gets it
More than 35 out of 100 (35%) of kidney cancers are diagnosed in people aged 75 and over. Kidney cancer is rare in people under 50.
Kidney cancer is diagnosed more often in men than women. This could be because in the past more men smoked cigarettes. Smoking increases your risk of getting kidney cancer.
How common it is
Kidney cancer is the 8th most common cancer in the UK (excluding non melanoma skin cancer).
Around 10,400 kidney cancers were diagnosed in the UK in 2012.