What causes bladder cancer?
Bladder cancer occurs when cells making up the bladder begin to grow and spread in an uncontrolled way, leading to the formation of a malignant tumour. This abnormal cell growth is caused by mutations in the genes that control cell replication, repair, and programmed death: genes that help cells to grow and divide may be switched on, while genes that regulate cell division, repair, and programmed death may be switched off. Sometimes the associated gene mutations are caused by exposure to carcinogenic chemicals or radiation, but they may also occur without any apparent external cause.
Is bladder cancer hereditary?
Population studies suggest the risk of bladder cancer is approximately 2-times higher if a first-degree relative (parent, child, or sibling) has had bladder cancer.1 However, it should be kept in mind that this estimate represents a statistical risk over a population and does not correspond directly to a person’s individual risk. A further aspect to consider is that family members may also share behaviours and/or environments that increase their bladder cancer risk, such as cigarette smoking. Overall, it is uncommon for bladder cancer to be caused by an inherited gene mutation. Instead, most of the gene mutations associated with bladder cancer are ‘acquired’, meaning that they develop during a person’s lifetime. Some acquired gene mutations are caused by exposure to toxins or chemicals that are recognised risk factors for developing bladder cancer, as discussed below.
Who is at risk of bladder cancer?
A risk factor refers to anything that increases the chance of developing a disease. Many factors influence an individual’s risk of bladder cancer, including personal characteristics, lifestyle choices, occupation, and environmental factors. In general, individuals with multiple risk factors are at highest risk (e.g., males over the age of 55 years who smoke). However, like any type of cancer, bladder cancer is complicated and difficult to predict: some people with multiple risk factors never develop the disease, while others may have bladder cancer in the absence of any known risk factor.
Bladder cancer risk factors
Knowing the factors that may put you at an increased risk of bladder cancer enables you to take simple precautions to lower your risk and protect your health. Combined with knowledge of the common symptoms of bladder cancer, awareness of risk also helps to inform decisions regarding diagnostic testing. A non-invasive genomic urine test like Cxbladder can help detect bladder cancer quickly and accurately at early stages, when treatment is most likely to be straightforward and effective.
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Demographic risk factors
Men are 4 times more likely than women to be diagnosed with bladder cancer.2
Bladder cancer mostly affects people over 55 years of age. In Australia, the average age of individuals diagnosed with bladder cancer is around 75 years.3
Rates of bladder cancer may vary among racial/ethnic groups. Available data indicate that bladder cancer occurs at a similar rate in Indigenous and non-Indigenous ethnicities in Australia.4
Lifestyle risk factors
Cigarette smoking is the most important risk factor for bladder cancer, causing around half of all cases. Chemicals in tobacco smoke that enter the bloodstream are filtered by the kidneys and excreted in urine, where they may adversely affect bladder cells. Smokers are at least 3 times as likely to get bladder cancer compared with non-smokers.4
Environmental risk factors
- Arsenic in drinking water
Arsenic has been associated with bladder cancer when present at significant levels in drinking water. The likelihood of potentially harmful levels of arsenic in water depends on locality and the water source being used (e.g., a private well versus a fully regulated municipal water supply).
Occupational risk factors
- Exposure to certain chemicals in the workplace
Responsible for an estimated 25% of all cases of bladder cancer,6 workplace exposure is the second major cause of bladder cancer behind smoking. Evidence strongly supports a link between bladder cancer and occupations within the dye, rubber, leather, and aluminium industries as well as dye users, machinists (e.g., metalworking machinists, textile machine operators), painters, mechanics, and truck drivers. Chemicals or substances implicated in workplace exposures include aromatic amines, polycyclic aromatic hydrocarbons, diesel engine exhaust, combustion products, leather dust, mineral oils, chlorinated solvents, creosote, herbicides/pesticides, and asbestos.7
If your job is associated with an increased risk, follow all workplace safety procedures to avoid exposure and ensure that any concerns are discussed with a doctor.
Other conditions that may increase bladder cancer risk
- Some medicines
The use of some medicines and certain chemotherapy drugs may be associated with an increased risk of bladder cancer.
- Chronic bladder inflammation / irritation
Chronic inflammation caused by conditions such as urinary tract infections, kidney/bladder stones, and indwelling urinary catheters has been associated with bladder cancer. However, the extent of any relationship between chronic bladder inflammation and cancer remains unclear.
- Bladder abnormalities
Certain congenital abnormalities of the bladder have been linked to increased rates of bladder cancer. In particular, a history of bladder exstrophy (fusion of the bladder and abdominal wall during fetal development) is known to greatly increase an individual’s bladder cancer risk.
- Previous bladder cancer
People who have had bladder cancer are prone to recurrence. Recurrence rates depend on the stage of the tumour at first diagnosis: 5-year recurrence is approximately 65% in patients with early stage, non-invasive tumours, and 73% in patients with slightly more advanced disease at first diagnosis.8
What affects bladder cancer survival?
Several factors are known to affect the survival rate of people with bladder cancer. Patient-related factors, such as age and overall health, and disease-related factors, such as the stage of the cancer at diagnosis, response to treatment, and whether the cancer is an initial or a recurrent episode are all relevant.
How do bladder cancer survival rates differ by disease stage?
Staging of bladder cancer provides information on the extent of cancer in the body and whether it has spread beyond the bladder; this information helps predict how likely the cancer will respond to treatment. Approximately half of bladder cancers are found at an early stage, when the cancer is in the surface layer of the bladder only (referred to as “in situ” or “non-invasive”). About one third of bladder cancers have spread to the deeper layers of the bladder wall but are still only in the bladder (“localised”); the remainder of cancers have spread into nearby tissues or lymph nodes (“regional”) or, rarely, to distant parts of the body (“distant”).
The overall 5-year survival rate for bladder cancer is 77%8 (i.e., an estimated 77% of bladder cancer patients would be expected to survive the effects of their cancer for 5 years or more). However, survival rate varies depending on the stage of the disease at diagnosis. For in situ/non-invasive bladder cancers the 5-year survival rate is very high (96%) whereas bladder cancers diagnosed at later stages have progressively lower survival rates (localised, 69%; regional, 37%; distant, 6%)8, which emphasises the importance of detecting bladder cancer at an early stage.
How do bladder cancer survival rates differ by age?
The 5-year survival for bladder cancer across stages is generally higher in younger individuals and decreases with increasing age:9
|Stage at Diagnosis||5-year survival rates for bladder cancer by age|
|< 50 years of age||50-64 years of age||65 years and older|
What to do if you are concerned about your bladder cancer risk
As the 5-year survival rates illustrate, the prognosis for bladder cancer is considerably more favourable when it is detected early (i.e., when it is small and has not spread beyond the bladder). Awareness of the risk factors and early symptoms associated with bladder cancer is therefore important. If you have any signs or symptoms of bladder cancer and believe you may be at elevated risk, reach out to your doctor and ask about Cxbladder.
Cxbladder is a non-invasive genomic urine test that quickly and accurately detects or rules out bladder cancer. The test combines clinical risk factor markers with genetic information, measuring five biomarker genes to detect the presence or absence of bladder cancer.
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Last Updated: 21 Apr 2021 09:35 am
- Koutros S, Decker KL, Baris D, et al. Bladder Cancer Risk Associated with Family History of Cancer. Int J Cancer. 2021 Jan 27. doi: 10.1002/ijc.33486. Epub ahead of print. PMID: 33506540.
- International Agency for Research on Cancer. Bladder. Source: Globocan 2020. Available at: https://gco.iarc.fr/today/data/factsheets/cancers/30-Bladder-fact-sheet.pdf.
- Cancer Australia. Bladder Cancer Statistics. https://www.canceraustralia.gov.au/affected-cancer/cancer-z/bladder-cancer/bladder-cancer-statistics.
- Cancer Australia. Cancer Incidence. https://ncci.canceraustralia.gov.au/diagnosis/cancer-incidence/cancer-incidence.
- American Cancer Society. Bladder Cancer Risk Factors. https://www.cancer.org/cancer/bladder-cancer/causes-risks-prevention/risk-factors.html.
- Centers for Disease Control and Prevention. Bladder Cancer Exposure and Risk. https://ephtracking.cdc.gov/showCancerBladderEnv.action.
- Colt JS, Karagas MR, Schwenn M, et al. Occupation and bladder cancer in a population-based case-control study in Northern New England. Occup Environ Med. 2011;68(4):239-49.
- Chamie K, Litwin MS, Bassett JC, et al. Recurrence of high-risk bladder cancer: a population-based analysis. Cancer. 2013;119:3219-3227.
- American Cancer Society. Survival Rates for Bladder Cancer. https://www.cancer.org/cancer/bladder-cancer/detection-diagnosis-staging/survival-rates.html.
- National Cancer Institute. SEER Explorer. https://www.seer.cancer.gov/explorer. Accessed January 7, 2021.
- American Cancer Society. Bladder Cancer Early Detection, Diagnosis, and Staging.
- American Cancer Society. Bladder Cancer Stages.
- American Cancer Society. Can Bladder Cancer be Found Early?
- American Cancer Society. Key Statistics for Bladder Cancer.
- American Cancer Society. What Causes Bladder Cancer?
- ASCO Cancer.Net. Bladder Cancer: Risk Factors.
- Cancer Research UK. Bladder Cancer.
- Cancer Research UK. Bladder Cancer Risks and Causes.
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