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Bladder cancer is the fourth most commonly diagnosed malignancy in men in the United States and the ninth most commonly diagnosed malignancy in U.S. women. It is estimated that 68,810 new cases of bladder cancer are expected to occur in the United States in 2008.
Bladder cancer is diagnosed almost twice as often in whites as in blacks of either sex. The incidence of bladder cancer among other ethnic and racial groups in the United States falls between that of blacks and whites. The incidence of bladder cancer increases with age. Approximately 80% of newly diagnosed cases in both men and women occur in people aged 60 years and older.
Since the 1950s, the incidence of bladder cancer has risen by approximately 50%. It is to be anticipated that, with the aging of the U.S. population, this trend will continue. In contrast, there has been a decrease of approximately 33% in bladder cancer mortality during the same interval (National Cancer Institute’s Surveillance, Epidemiology, and End Results program, 1973–1997). It is estimated that 14,100 Americans will die of bladder cancer in 2008.
The age-adjusted mortality from bladder cancer has decreased in all races and sexes over the past 30 years, but blacks and women have a disproportionately higher mortality rate than that of white males. These changes may reflect earlier diagnosis, better therapy, less exposure to carcinogens, or some combination of these factors.
More than 90% of cancers in the bladder are transitional cell carcinomas (TCC), also called urothelial cancer. Other important histologic types include squamous cell carcinoma and adenocarcinoma. Urothelial cancer can also rarely develop in the lining of the renal pelvis, ureter, prostate, and urethra.
Risk Factors
There are no definitive studies on the prevention of bladder or other urothelial cancers. Reduction in environmental and occupational exposures would presumably reduce urothelial cancer risk. Differences in age, gender, race, and geographic distribution may reflect differences in environmental and occupational exposure to possible toxicants. Relevant exposures include chemical exposures; cigarette smoking; infection with bacteria, parasitic fungi, or viruses; harboring bladder calculi; and treatment with certain chemotherapeutic agents.
Several populations with a variety of exposures appear to be at higher risk of developing bladder cancer. By far the greatest known environmental risk factor in the general population is tobacco, especially cigarette smoking, with individuals who smoke having a fourfold to sevenfold increased risk of developing bladder cancer than individuals who have never smoked. Risk is reduced with cessation of smoking, but a relatively small decrease in incidence is seen for the first 5 to 7 years after cessation. Even after 10 years, the risk of an individual developing bladder cancer is still almost twice that of an individual who has never smoked.
Among the chemicals implicated in smoking-induced bladder cancer are aminobiphenyl and its metabolites. It is possible that inherited and inducible enzymes are important in the activation and detoxification of aminobiphenyls and other putative bladder carcinogens. These enzymes include N-acetyltransferase 2 (NAT2), cytochrome P450 1A2 (CYT 1A2), and glutathione S-transferase M 1.Several studies have indicated that specific genotypes and phenotypes of these enzymes and their activities, particularly in the liver and urothelium, are associated with susceptibility to smoking-induced bladder cancer and bladder cancer induced by other aryl amines, particularly in industrially exposed populations. Not all of these studies, however, have been well controlled for active or former smoking histories.
A variety of industrial exposures have also been implicated as risk factors for developing bladder cancer, primarily aromatic amines present in the production of dyes and benzidine and its derivatives; combustion gases and soot from coal, possibly chlorinated aliphatic hydrocarbons; chlorination by-products in heated water; and certain aldehydes (e.g., acrolein used in chemical dyes and in the rubber and textile industries).
Occupations reported to be associated with an increased risk of bladder cancer include those that involve organic chemicals such as dry cleaners, paper manufacturers, rope and twine makers, and workers in apparel manufacturing.
It is estimated that 5% to 15% of patients in the United States who eventually die from bladder cancer will have strong exposure histories to the above-named environmental factors (other than smoking).
The use of contaminated Chinese herbs is also reported to be a risk factor. The prime carcinogen in these herbs appears to be aristolochic acid (AA) extracted from species of Aristolochia. Because of the diversity of Chinese herbal regimens used in addition to AA, other unidentified phytotoxins may also play a role. The chronic nephropathy associated with ingestion of herbs contaminated with A. fangchi has been linked to urothelial carcinoma of the renal pelvis and ureter. Herbs with A. fangchi are banned from Belgium, Canada, Australia, and Germany but are still available in the United States.
Ingestion of large quantities of arsenic in well water has also been associated with numerous malignancies, including TCC of the bladder. Similar endemic pockets of bladder cancer are found in other regions with high arsenic concentrations in drinking water. In South Taiwan, arsenic blackfoot disease is endemic.
Additional risk factors associated with more aggressive forms of bladder cancer include prolonged exposures to urinary foreign bodies and infections; neuropathic bladder and associated indwelling catheters; Schistosoma haematobium bladder infections (Bilharzial bladder cancer); exposure to the cancer chemotherapy agent cyclophosphamide and perhaps other alkylating agents, such as ifosfamide (although the use of mesna in conjunction with these agents may reduce the incidence); and pelvic radiation therapy for other malignancies. Renal transplant recipients appear to have an increased incidence of bladder cancer.
Urothelial tumors other than TCC include adenocarcinoma, squamous cell carcinoma, and metastatic adenocarcinoma. Risks for squamous cell tumors in the bladder include indwelling catheters, and haematobium cystitis. You can find a good medication online pharmacy, you can consult with your doctor which contains the necessary medicines.
Adenocarcinomas account for less than 2% of primary bladder cancers, including metastases from the rectum, stomach, endometrium, breast, prostate, and ovary. |
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