Kidney cancer - Causes and risk factors

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

The three main risk factors for kidney cancer are:

• obesity
• smoking
• family history and genetics

Obesity

Obesity is a significant risk factor for kidney cancer.

A study carried out by Cancer Research UK in 2011 found that around a quarter of  kidney cancer cases are associated with being overweight or obese (25% of cases in men and 22% in women).

There's a strong link between someone’s body mass index (BMI) and their risk of developing kidney cancer. You can read more about how BMI is calculated, and work out your BMI using the healthy weight calculator. 

A BMI score of 25 or above has been shown to increase a person's chances of developing kidney cancer. Those with a a BMI score of 30 or above are at particularly high risk.

This may be because overweight or obese people, particularly women, have higher levels of a hormone called oestrogen in their body. It's 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 also 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're one-and-a-half times more likely to develop kidney cancer compared to a non-smoker. This increases to twice as likely if you smoke 20 or more cigarettes a day.

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

Family history and genetics

If you have a close family member (parents, brothers, sisters or a child) who's been diagnosed with kidney cancer, you're about twice as likely to develop kidney cancer yourself.

Examples of inherited genetic conditions and syndromes that increase your risk of developing kidney cancer include:

• tuberous sclerosis – a rare genetic condition that causes multiple non-cancerous (benign) tumours to grow in the body; it’s autosomal dominant, which means you only have to inherit the faulty gene from one parent to get it; about one in every 100 people with tuberous sclerosis will develop kidney cancer
• hereditary papillary kidney cancer – a rare form of cancer caused by faulty genes inherited from your parents; it’s autosomal dominant and causes small, slow-growing, cancerous tumours to develop in the kidneys, which can sometimes spread
• hereditary leiomyomatosis and renal cell carcinoma (HLRCC) – a rare, autosomal dominant form of cancer, where cancerous tumours develop from smooth muscle tissue (leiomyomatas); people with HLRCC have a 10-16% increased risk of developing kidney cancer
• Von Hippel-Lindau syndrome – a rare genetic syndrome that causes small non-cancerous tumours to develop inside the nervous system; VHL is also autosomal dominant and about 4 out of 10 people who have it develop kidney cancer
• Birt-Hogg-Dubé syndrome – an inherited syndrome that causes non-cancerous tumours to develop in the hair follicles of the skin; they usually occur on the face, neck and torso

Other possible risk factors

There are also a number of other possible risk factors for developing kidney cancer, including:

• mild painkillers – some mild painkillers have been linked to an increased risk of developing kidney cancer; NSAIDs, such as ibuprofen, may slightly increase the risk, although occasional use or low doses are unlikely to be harmful
• kidney disease – if you have kidney failure and need to have regular dialysis (treatment to replicate the functions of the kidneys), your risk of developing kidney cysts and kidney cancer is increased
• high blood pressure (hypertension) – high blood pressure is a known risk factor for kidney disease, and you're up to twice as likely to develop kidney cancer if you have raised blood pressure