Bladder cancer: A common form of cancer that begins in the lining of the bladder. The most common warning sign is blood in the urine. Symptoms include pain during urination, frequent urination, and feeling the need to urinate without results. A diagnosis of bladder cancer is supported by findings in the medical history, physical examination, examination of the urine, and intravenous pyelogram (IVP). Confirmation of the diagnosis requires a biopsy, usually using a cystoscope. The bladder is lined with cells called transitional cells and squamous cells. A tumor may grow through the lining into the muscular wall of the bladder and extend into nearby organs such as the uterus or vagina (in women) or the prostate gland (in men). When bladder cancer spreads beyond the bladder, the malignant cells are frequently found in nearby lymph nodes and may have spread to other lymph nodes or other places, including the lungs, liver, or bones. Risk factors for bladder cancer include age over 40 years, race (Caucasians are at twice the risk of African-Americans and Hispanic-Americans, with Asian-Americans at least risk), gender (men are two to three times more likely to get bladder cancer), family history of bladder cancer, use of tobacco (which is a major risk factor), occupational exposures (for example, workers in the rubber, chemical, and leather industries, hairdressers, machinists, metal workers, printers, painters, textile workers, and truck drivers), and prior treatment with cyclophosphamide or arsenic exposure. Treatment depends on the growth, size, and location of the tumor. Surgical operations are commonly needed. Chemotherapy, biological therapy, or radiotherapy may also be used.