What are the risk factors for bladder cancer?
Some environmental or personal elements can increase the probability of getting a specific disease like bladder cancer. Those are the so called risk factors. Some risk factors can be reduced or avoided, like cigarette smoking. Others, like a person’s age or family history, are unchangeable. The more risk factors a person is exposed to, the more likely it is to get the particular disease.
Nevertheless, risk factors are just indicators and do not necessarily mean that an exposed person eventually develops this disease. Conversely, absence of any risk factor does not give a complete protection. For example, not all smokers will get bladder cancer while there are simultaneously bladder cancer patients which have never smoked.
Smoking is the strongest risk factor for bladder cancer. A regular cigarette smoker has a 3-fold higher risk to get bladder cancer compared with a non-smoking person. About half of all bladder cancers are caused by smoking habits.
Tobacco smoke contains carcinogens (cancer-causing substances) which are absorbed from the lungs and distributed by the bloodstream. They are finally filtered by the kidneys for flushing out of the body via urine. In the urine, they are concentrated in order for the body to safe water loss. In their higher concentration they are more aggressive and can damage the cells lining the inside of the bladder over time, increasing the risk of cancer development
Several organic industry chemicals can cause bladder cancer by similar mechanisms than tobacco smoke. Most infamous are aromatic amines such as benzidine and beta-naphthylamine.
Workers in the following industries have an increased risk: manufacturers of paint products, rubber, leather, textiles as well as other workers coming into regular contact with these chemicals, such as painters, machinists, printers, hairdressers and truck drivers.
If good workplace safety practices are installed, those risks can be minimized.
Low Fluid Consumption
Low fluid intake may increase this risk of bladder cancer because irritating substances are left in the bladder longer. Likewise, people drinking plenty of fluids daily have lower bladder cancer rates.
Drinking water contaminated with arsenic has been linked to an increased bladder cancer risk.
As for many other malignant tumours, the risk of getting bladder cancer increases with age. The average age of fist diagnosis is 73. More than 90 % of bladder cancer patients are older than 55.
The risk of getting bladder cancer is much higher for men than for women.
Having family members with bladder cancer poses an additional risk factor. This can have different reasons.
Sometimes, all family members are exposed to the same carcinogen, for example by working in the same industry or by collective smoking habits. In other cases, inherited gene variants (e.g. GST or NAT) are responsible for slower breakdown of certain carcinogens.
There are also other rare inherited diseases linked to increased bladder cancer risk, for example:
- Mutations in the retinoblastoma gene (RB1) usually causes eye cancer in infants but also increases bladder cancer risk.
- Cowden disease, caused by PTEN mutations increases the risk of many malignant diseases, amongst which is bladder cancer.
- Lynch syndrome is mainly associated with colon cancer, but also increases the risk of bladder cancer.
Personal History of Bladder Cancer
Cancer can form in all regions of the urothelium, such as in the lining of the kidneys, ureter and urethra. Cancer in any of these areas can increase the risk of another tumour in this layer of cells, regardless if the primary tumour has been removed completely. Bladder cancer patients need to be closely monitored following treatment because additional tumours in the urothelium are very common.
Chronic Bladder Irritations and Infections
Several causes of chronic balder irritation have been linked to a special from of bladder cancer (squamous cell carcinoma). Amongst those are regular urinary infections, kidney and bladder stones and bladder catheters left in place over a long time. It is unclear, however, if they actually cause bladder cancer.
A regionally specific risk factor for irritation-caused bladder cancer is schistosomiasis, an infection with a parasitic worm called Schistosoma hematobium. In countries where this parasite is common (Middle East and Northern Africa), squamous cell carcinoma of the bladder is much more frequent.
Bladder Birth Defects
During embryonic development a connection between the belly button and the bladder forms that disappears before birth (urachus). Rarely, a part of this connection remains after birth, and can develop into adenocarcinomas. In another birth defect called exstrophy, the bladder and abdominal wall fusetogether, leaving the inner lining of the bladder exposed to other areas of the body. Even following corrective surgery, people who have or had this problem are at a higher risk for bladder cancer.
Chemotherapy and Radiation Therapy
Long-term use of cyclophosphamide, a formerly frequently used chemotherapeutic drug in breast cancer treatment, is associated with a heightened risk of bladder cancer. Drinking extra fluids while taking this drug can help protect the bladder from irritation and lower this risk. Radiation aimed at the pelvis is also considered a risk factor for bladder cancer.