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Risks and causes

Find out what causes bladder cancer and how you can reduce your risk.

How common it is

Around 10,100 people are diagnosed with bladder cancer each year in the UK. It is the 10th most common cancer in the UK (not counting non melanoma skin cancer) and the 8th most common cancer in men.

Who gets it

Bladder cancer usually takes a long time to develop, so it is most common in older people. Most people with bladder cancer are over 60 years old. It is rare in people under 40.

More men than women get bladder cancer. This may just be because more men than women have smoked or been exposed to chemicals at work in recent decades. 

We don’t know what causes most bladder cancer. But some factors may increase your risk of getting it.

What a risk factor is

Anything that can increase your risk of getting a disease is called a risk factor.

Different cancers have different risk factors.­ Having one or more of these risk factors doesn't mean you will get that cancer.

Risk factors for bladder cancer

Smoking cigarettes definitely increases the risk of bladder cancer. Over a third of all bladder cancers are caused by smoking. 

Your risk of getting bladder cancer if you smoke is up to 4 times that of someone who has never smoked. People with the highest risk are those who:

  • smoke heavily
  • started smoking at a young age
  • have smoked for a long time

Smoking cigars and pipes also increases your risk.

How smoking may increase your risk

Chemicals in the smoke get into the bloodstream. They are then filtered out of the blood by the kidneys and end up in the urine. When the urine is stored in the bladder, these chemicals are in contact with the bladder lining.

Chemicals called arylamines are known to cause bladder cancer. Arylamines in cigarette smoke may be the cause of the increased risk.

For some people who smoke, passing urine more often may reduce the risk. But there is not enough evidence to show that this is true for everyone.

Second hand smoking

Research looking at second hand smoking (passive smoking) and bladder cancer risk did not find a link. Some studies have tried to find a link between second hand smoke and bladder cancer risk in children but the results have varied.

If you have been diagnosed with bladder cancer, It is worth finding out if you have ever been exposed to a chemical mentioned here. If you have, talk to your urologist or cancer doctor.

Arylamines

A group of chemicals called arylamines are known to cause bladder cancer. Some of these chemicals have been banned in the UK for over 50 years. But you may have been exposed to them if you work in industries such as rubber or plastics manufacture. It can take up to 25 years for a bladder cancer to develop.

Arylamines that increase risk of bladder cancer include:

  • aniline dyes
  • 2-Naphthylamine
  • 4-Aminobiphenyl
  • xenylamine
  • benzidine
  • o-Toluidine

Polycyclic aromatic hydrocarbons

A group of chemicals called polycyclic aromatic hydrocarbons (PAHs) increase the risk of bladder cancer. You may have been exposed to them if you have worked in:

  • industries where people handle carbon or crude oil, or substances made from them
  • any industry involving combustion, such as smelting

Other jobs

Some other jobs have been linked to an increased risk of bladder cancer. These include:

  • bus and taxi drivers and railroad workers
  • metal casters, machine setters and operators
  • leather workers
  • blacksmiths
  • hairdressers
  • mechanics
  • miners
  • painters

In all these jobs the increase in risk of bladder cancer is below 35%.

If you have a diagnosis of bladder cancer and know that you have been exposed to any of these chemicals, you may be able to claim an allowance from the government. This is called an Industrial Injuries Disablement Benefit from the Department for Work and Pensions. Discuss this with your doctor.

Chlorine and trihalomethanes

Chlorine is used to disinfect drinking water and swimming pools. It breaks down into chemicals called trihalomethanes (THMs) that stop harmful bacteria from growing. Researchers have looked at whether exposure to THMs by drinking chlorinated water can increase bladder cancer risk. 

Some research studies seem to show that long term drinking of tap water with high levels of THMs may increase the risk of bladder cancer. But findings are mixed.

In some studies the increase in risk was only seen in men. Bladder cancer risk in women was not linked to drinking tap water. Other studies have shown a reduced risk of bladder cancer in people who drink a lot of water, especially if they empty their bladder often. But these studies also have limitations, so we don't know for certain. 

There is some evidence that swimming, bathing or showering in chlorinated water can increase your risk of getting bladder cancer. This happens when the chemicals are absorbed through the skin or breathed in as water droplets.

But it is important to remember that disinfecting water reduces the risk of serious infectious diseases. So the overall risk of not chlorinating water is likely to be higher than the overall risk of being exposed to THMs.

Radiotherapy to the pelvic area for other cancers can increase your risk of bladder cancer. This treatment is given for cervical cancer, prostate cancer, fallopian tube cancer, testicular cancer and womb cancer.

Treatment for some other cancers may also increase risk. These include head and neck cancers, lung cancer and kidney cancer. Radiotherapy or chemotherapy may increase the risk. Or it may be that these cancers share risk factors with bladder cancer.

Treatment with the chemotherapy drug cyclophosphamide also increases your risk of getting bladder cancer.

Diabetes

Having diabetes increases your risk of getting bladder cancer by around a third compared with people who don’t have diabetes.

This is likely to be due to the drug pioglitazone, which is used to treat type 2 diabetes. It has been found to increase the risk of bladder cancer.

Pioglitazone is a type of the thiazolidinedione group of drugs. But other drugs in this group do not seem to increase the risk. The type of treatment used for type 2 diabetes depends on the stage of diabetes. The diabetes stage may also affect these findings. 

Spinal cord injury

People with a spinal cord injury have a higher risk of getting bladder cancer than the general public. This may be because they are more likely to have a urinary catheter, bladder or urine infections, or bladder stones.

Systemic sclerosis

Women who have systemic sclerosis have a higher risk of getting bladder cancer than the general public.  This may be due to a drug called cyclophosphamide, which is used to treat the condition.

Kidney transplant

People who have had a kidney transplant have a higher risk of getting bladder cancer than the general public.

Crohn’s disease

People with Crohn's disease have a higher risk of getting bladder cancer than people who do not have Crohn's disease.

Bladder infections

Past research seemed to show that you may be more at risk of getting bladder cancer if you have had many bladder infections, or a chronic bladder infection. The risk is particularly high for a type called squamous cell bladder cancer.

But one recent study did not find an increase in risk for people with a history of common bladder infections. And another study showed a decrease in risk in women who have had many bladder infections. We need more research to find out if there is a link between bladder infections and bladder cancer.

Research from 1991 showed that smokers who have had many bladder infections may have a risk of bladder cancer 10 times higher than the general population. But there have not been any more studies to confirm this.

Infection is a much less common cause of bladder cancer than smoking or workplace chemicals.

Gonorrhoea

Research has found that men who have had gonorrhoea have an increased risk of bladder cancer. And for those men who smoke and have gonorrhoea, the risk may be even higher. 

Parasitic infection

In the developing world, parasitic infection is the main cause of bladder cancer. A parasite called bilharzia or schistosomiasis is widespread in many countries. It increases the risk of getting squamous cell bladder cancer. But parasitic infection is extremely rare in the UK.

Bladder stones

Bladder stones are little lumps of calcium that can form in the urinary system. If you have bladder stones (sometimes called bladder calculi) you may be more at risk of getting squamous cell bladder cancer. This is because stones can cause chronic infection. But you would need to suffer from this for a long time before it would increase your risk of bladder cancer.

Researchers have looked at many different factors in our diet to see if any of them affect bladder cancer risk. Most of the research findings do not show any clear links.

Selenium

Selenium is a nutrient found in various foods. It has been shown to protect against bladder cancer in some studies.

Vitamin D

Having higher levels of vitamin D has been found to lower your risk of getting bladder cancer.

Fruit and vegetables

Some research suggests that having eating more fruit and vegetables may lower your bladder cancer risk.

Alcohol

Drinking alcohol does not have affect your risk of getting bladder cancer. But it does increase your risk of getting several other cancers, including breast and bowel cancer. 

Your risk of developing another cancer anywhere in the urinary tract is higher if you have previously been successfully treated for a bladder cancer. This includes:

  • any part of your bladder that is still there after your treatment
  • the tubes that connect the kidney and the bladder (the ureters) including the part within the kidney (the renal pelvis)
  • the tube leading from the bladder to the outside of the body (urethra)

You have regular checkups after treatment so that your specialist can find any new cancer at its earliest stage.

Having had transitional cell cancer of other parts of the urinary tract (such as the ureters, urethra or renal pelvis) also increases your risk of getting bladder cancer.

In a few families, bladder cancer is associated with an inherited faulty gene. But this is very rare.

If your relative was diagnosed before the age of 45, it is more likely that their cancer was caused by a gene fault. But family cancer patterns are influenced by behaviour too. Often cancers may seem to run in families because the family members share behaviours, such as smoking, which increase the risk of getting bladder cancer. 

Overall, you are statistically more at risk if you have a first degree relative (a parent, child, sister or brother) with bladder cancer. But this is a statistical risk. It can only tell you about risk in a whole population, not your individual risk as a person.

Some research has shown that women who have a menopause before the age of 45 have their risk of bladder cancer increased by around half compared with women who have their menopause at the age of 45 or later.

The increase in risk is higher in women who have early menopause after having both their ovaries removed for medical reasons.

Women who have had children have a lower risk of getting bladder cancer than women who have not had any children. 

As a baby develops inside the mother there is a connection between the baby's bladder and belly button (umbilicus). This connection is called the urachus. It usually disappears before the baby is born.

Very rarely, this connection can remain after birth. This can increase the risk of a rare type of bladder cancer called adenocarcinoma.

Another very rare birth defect called extrophy can increase a person’s risk of developing bladder cancer later in life.

Extrophy happens when the bladder and urethra do not form properly. The bladder does not form its normal round shape but becomes flat and exposed to the outside of the body. It is turned inside out. With the bladder outside the body and not protected by skin covering, it can easily become infected. This can eventually lead to adenocarcinoma of the bladder.

Some research has suggested that using hair dye to colour your own hair may lead to an increased risk of bladder cancer. But other, more recent research has suggested that it does not.

There is some evidence that hair dye can increase the risk of bladder cancer for hairdressers and barbers who have been working in the industry for 10 or more years. This is because they are working with these chemicals all the time. But this risk can be reduced by using non touch hairdressing techniques. Also, some of the chemicals that can increase the risk of bladder cancer have been banned. 

One research study has shown that people who have Down’s syndrome have a lower risk of getting bladder cancer. But more research is needed.

Some research has shown no difference in risk of getting bladder cancer for people who are a normal weight and people who are overweight. But a recent study showed that overweight men were more at risk of developing bladder cancer. The researchers concluded that these results may have been affected by smoking.

Research has shown that physically active people have a lower risk of getting bladder cancer than people who are less physically active.

Other possible causes

Stories about potential causes of cancer are often in the media. It isn’t always clear which ideas are supported by good evidence.

You might hear about possible causes we haven’t included here. This is because there is no evidence about them or because it is not clear what the evidence shows.

Detailed information on risks and causes

Information and help

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