There are several known risk factors for bladder cancer. By far the biggest cause of bladder cancer in the United States is cigarette smoking. Other risk factors are exposure to aniline dyes, recurrent urinary tract infections, chronic foley catheters, bladder stones, and previous radiation to the pelvis as treatment for another cancer. Also, there may be a small increased risk for people who color their hair with permanent hair colors, with the risk increased in those people who dye their hair more often or who started coloring it at a younger age. Dietary factors may also affect the risk of bladder cancer.
In a review of data from the Surveillance, Epidemiology, and End Results database, it was found that patients with other primary tumors had a tenfold higher risk of bladder cancer compared with the general population. The risk was highest in patients who were previously diagnosed with prostate cancer. Infection of the bladder by a parasite called schistosomiasis markedly increases the risk of bladder cancer. Although this infection is common in Egypt and surrounding countries, it is rare in the United States. Tobacco: Cigarette smoking accounts for 25% to 65% of all cases of bladder cancer in the United States.
It increases the risk of bladder cancer by up to four times compared with someone who has never smoked. As you might expect, the risk increases as the number of cigarettes increases, the number of years of smoking increases, and by the degree of inhalation with each puff. This applies to both men and women. The risk is even higher with the use of air-cured “black” tobacco because it has a higher concentration of chemicals than flue-cured “blond” tobacco.
The good news is that quit-ting smoking decreases your risk; thus, it is never too late to quit. Other forms of tobacco, such as cigars and smokeless tobacco, also increase the risk of cancer, although to a lesser degree. It is not clear what chemical in the cigarette smoke is responsible for bladder cancer. Some people clear the chemicals from cigarette smoke more slowly than others do. These people, called slow acetylators, appear to be at increased risk for bladder cancere.
Occupational risk factors: Exposure to aniline dyes is the most common industrial risk factor for bladder cancer. Aniline dyes are byproducts of burning coal. These dyes have been used for staining or coloring wood and textiles. Other occupational chemicals that have also been associated with bladder cancer include 2-naphthylamine, 4-aminobiphenyl, 4-nitrobiphenyl, 4-4-diaminobiphenyl (benzidine), and 2-amino-1-naphthol, certain aldehydes used in rubber and textile manufacturing, combustion gases and soot from coal, and possibly hydrocarbons. An increased risk has been reported in all of the following occupations: autoworker, painter, truck driver, drill press operator, leather worker, metal worker, machine operator, dry cleaner, paper manufacturer, rope and twine maker, dental technician, barber, hairdresser, physician, apparel manufacturer, and plumber.
Phenacetin: Phenacetin is a pain medication that is no longer available in the United States, although it is still available in other countries. Large doses have been shown to increase the likelihood of developing bladder cancer. Pelvic radiation: Pelvic radiation increases the risk of developing bladder cancer. Women who have undergone radiation therapy for uterine cancer or ovarian cancer in the past have a twofold to four-fold higher risk of developing bladder cancer. The increased risk is most apparent among women who received radiation doses between 30 and 60 Gy. The risk of bladder cancer increases even more if chemotherapy was combined with the radiation.
Similarly, men who have had radiation therapy for prostate cancer also have an elevated risk of bladder cancer. In those males who develop bladder cancer after external beam radiation therapy for prostate cancer, the cancers occurred 5.5 years, on average, after the radiation therapy. Chemotherapy and immunosuppression: Chemotherapy with the drug cyclophosphamide (cytoxan) is associated with up to a ninefold increased risk of developing bladder cancer. These cancers tend to be more aggressive as a group. The use of the medication MESNA at the time of cyclophos-phamide administration helps protect the bladder from irritation and decreases the risk of developing bladder cancer.
A similar chemotherapy agent, ifos-famide (Ifex) is also associated with increased risk of developing bladder cancer. Also, patients who have had a kidney transplant or other organ transplants and are on immunosuppression (steroids and other medications) are known to have a higher risk for bladder cancer. Dehydration: Individuals who typically take in very little fluids are at increased risk of developing bladder cancer. Minimizing fluid intake causes the urine to become more concentrated and increases the amount of time between voiding. Holding concen-trated urine for longer periods of time likely plays a role in this increased risk.
Arsenic: Arsenic in drinking water is associated with an increased risk of developing bladder cancer. Bladder augmentation: Individuals who undergo bladder augmentation, a surgical procedure whereby the bladder is made larger by attaching a patch of intestine—small intestine or large intestine, rarely the stomach—are at increased risk for developing bladder cancer. The incidence of developing cancer per decade following augmentation surgery is 1.5% for ileal (small intestine)/colonic and 2.8% for gastric (stomach) augmentations. Patients with ileal or colonic bladder augmentations for congenital bladder abnormalities have a 7–8 fold risk, and gastric (stomach) augments have a 14–15 fold increased risk of developing bladder cancer compared to the general population. It is rec-ommended that, given the increased risk, individuals undergo routine surveillance starting approximately 10 years after the augmentation surgery.