Overview of epidemiology
Bladder cancer is a common disease worldwide. Incidence varies across the globe, with the highest burden of disease in developed countries. The less-developed countries are following closely, with increasing incidence as bladder cancer emerges as an important cause of morbidity and mortality all around the world. These observed disease trends are driven by both the ageing populations in developed nations as well as increasing exposure to environmental carcinogens in less-developed countries.
In published data, bladder cancer is consistently one of the top 20 cancers in both males and females. Age-standardized global incidence rates have been quoted as 2.5 per 100,00 in females and as high as 10.1 per 100,000 in males.
According to the World Health Organization, the single most important environmental risk factor for bladder cancer is tobacco use. Smoking is associated with a two- to three-fold increase in bladder cancer incidence compared with non-smokers. While the bladder itself is not directly exposed to tobacco smoke, it is well-established that polyaromatic hydrocarbons that circulate in the blood stream of smokers are largely responsible for the carcinogenic effects on the urothelium. Another risk factor that is worth mentioning as it contributes to bladder cancer incidence is occupational carcinogens. This is why underwriters must always be on high alert when dealing with certain occupations particularly if there is a classic history of hematuria.
Examples of such occupations are:
- Dry cleaners
- Paper production workers
- Rope-and-twine industry workers
- Dental workers
In developing countries, chronic bladder infection with Schistosoma haematobium or so-called bilharzia is an important risk factor for squamous cell carcinoma (SCC) of the bladder, especially in regions like Egypt where this parasitic infection is endemic. The risk factors that lead to cancer are:
- Worm burden
- Chronicity of infection
- Host inflammatory response
- Concentration of N-nitrosamines in urine
Bladder cancer can also be directly correlated with other medical treatments, for example, previous pelvic radiation, and chemotherapy with cyclophosphamide, which increases the risk of bladder cancer via exposure to acrolein, a urinary metabolite of cyclophosphamide. Other cases that are at risk of bladder cancer are spinal cord injury patients that require long-term indwelling catheters, which have shown a multi-fold increase in the risk of developing SCC of the bladder. The mechanical/irritant effect of the in-situ catheter is deemed a likely pathophysiological mechanism.
In Western countries and the U.S., the life time probability of a white male developing bladder cancer is estimated at one in 25. The overall survival over eight years is 75% according to SEER data published in the Oncologist 2003, but males have a higher five-year survival rate by all stages compared with females.
It is worth mentioning that, in the developed world, the overall mortality associated with bladder cancer has been reduced significantly over the past two decades. This is attributable to several factors of which the most important are:
- Tobacco control measures resulting in reduced smoker prevalence
- Reduced occupational exposure to aromatic amines
- Early bladder cancer detection and intervention
There is no strong association between genetic risk factors and bladder cancer. Smoking emerges as the single most important risk factor for this disease.Read More +