Causes and risk factors

The exact cause of kidney cancer is unknown, although there are risk factors that can increase the chances of the condition developing.

Increased risk

The main risk factors for kidney cancer are:

• obesity
• smoking
• family history

Obesity

Obesity is a particularly important risk factor for kidney cancer in women.

Research has found that there is a strong link between someone’s Body Mass IndexBMI (BMI) and their risk of developing kidney cancer.

Read more about how BMI is calculated, or work out your BMI using the healthy weight calculator.

A BMI score of 25 or above has been shown to increase the chances of developing kidney cancer.

A BMI score of 30 or above has been shown to signficantly increase the chances of developing kidney cancer.

This may be because overweight or obese people, particularly women, have higher levels of a hormone called oestrogen in their body. It is thought that excess levels of oestrogen may stimulate the growth of cancerous cells.

Cases of kidney cancer have been increasing over the last 40 years, which has been linked to rising obesity levels.

Smoking

Smoking is a significant risk factor for developing kidney cancer, and the more you smoke the greater the risk.

For example, research has shown that if you regularly smoke 10 cigarettes a day, you are one and a half times more likely to develop kidney cancer compared to a non-smoker. This is increased to twice as likely if you smoke 20 or more cigarettes a day.

It is not clear why smoking increases your chances of developing kidney cancer.

Family history

People with close family members that have been diagnosed with kidney cancer are about twice as likely to develop kidney cancer themselves.

Other conditions and risks

A number of other possible risk factors for kidney cancer include:

• exposure to certain chemicals, such as asbestos and cadmium
• cocaine misuse: a chemical called phenacetin used by criminals to ‘cut’ cocaine (dilute it) can cause kidney cancer
• kidney transplant – people who have had a kidney transplant have an estimated 1 in 100 chance of developing kidney cancer in their remaining ‘native’ kidney
• dialysis – dialysis is a treatment that is designed to replicate the functions of the kidneys, people who require dialysis are three times more likely to develop kidney cancer than the population at large
• tuberous sclerosis – a rare genetic condition that causes multiple non-cancerous tumours to grow in the body, an estimated 1 in every 100 people with tuberous sclerosis will develop kidney cancer
• Von Hippel-Lindau disease – another rare genetic condition that causes small non-cancerous tumours to develop inside the nervous system, people with the condition have about a one in three chance of developing kidney cancer
• high blood pressure (hypertension) – people with high blood pressure are up to twice as likely to develop kidney cancer.