Bladder cancer is a common urologic cancer. The most common type of bladder cancer in the United States is urothelial carcinoma, formerly known as transitional cell carcinoma (TCC). The urothelium in the entire urinary tract may be involved, including the renal pelvis, ureter, bladder, and urethra.

The clinical course of bladder cancer carries a broad spectrum of aggressiveness and risk. Low-grade, superficial bladder cancers have minimal risk of progression to death; however, high-grade muscle-invasive cancers are often lethal.

Pathophysiology: Almost all bladder cancers are epithelial in origin. The urothelium consists of a 3- to 7-cell mucosal layer within the muscular bladder. Of these urothelial tumors, more than 90% are transitional cell carcinomas. However, up to 5% of bladder cancers are squamous cell in origin, and 2% are adenocarcinomas. Nonurothelial primary bladder tumors are extremely rare and may include small cell carcinoma, carcinosarcoma, primary lymphoma, and sarcoma.

Bladder cancer is often described as a polyclonal field change defect with frequent recurrences due to a heightened potential for malignant transformation. However, bladder cancer has also been described as a problem with implantation and migration from a previously affected site.

The World Health Organization classifies bladder cancers as low grade (grade 1 and 2) or high grade (grade 3). Tumors are also classified by growth patterns: papillary (70%), sessile or mixed (20%), and nodular (10%). Carcinoma in situ (CIS) is a flat, noninvasive, high-grade urothelial carcinoma. The most significant prognostic factors for bladder cancer are grade, depth of invasion, and the presence of CIS.

Upon presentation, 55-60% of patients have low-grade superficial disease, which is usually treated conservatively with transurethral resection and periodic cystoscopy. Forty to forty-five percent of patients have high-grade disease, of which 50% is muscle invasive and is typically treated with radical cystectomy.

Less than 5% of bladder cancers in the United States are squamous cell carcinomas (SCCs). However, worldwide, SCC is the most common form, accounting for 75% of bladder cancer in underdeveloped nations. In the United States, SCC is associated with persistent inflammation from long-term indwelling Foley catheters and bladder stones. In underdeveloped nations, SCC is associated with bladder infection by Schistosoma haematobium.

Adenocarcinomas account for less than 2% of primary bladder tumors. These tumors are observed most commonly in exstrophic bladders and respond poorly to radiation and chemotherapy. Radical cystectomy is the treatment of choice.

Small cell carcinomas are aggressive tumors associated with a poor prognosis and are thought to arise from neuroendocrine stem cells.

Carcinosarcomas are highly malignant tumors that contain both mesenchymal and epithelial elements.

Primary bladder lymphomas arise in the submucosa of the bladder and are treated with radiation therapy.

Leiomyosarcoma is the most common sarcoma of the bladder.

Rhabdomyosarcomas most commonly occur in children and carry a poor prognosis.

Frequency:

—      In the US: Bladder cancer is the fourth most common cancer in men in the United States, after prostate, lung, and colorectal cancer. Bladder cancer is the 10th most common cancer in women. From 1985-2000, the number of patients diagnosed annually with bladder cancer increased by 33%. An annual cohort of 300,000-400,000 patients with bladder cancer is reported in the United States. The recurrence rate for superficial transitional cell cancer of the bladder is high, and as many as 80% of patients have at least one recurrence.

—      Internationally: In developed countries, 90% of bladder cancers are TCC. In developing countries, 75% of bladder cancers are SCCs, and most of these cancers are secondary to S haematobium infection.

Mortality/Morbidity: In 2004, an estimated 60,200 new patients were diagnosed with bladder cancer in the United States, and 12,700 of those patients died from the disease.

Race: Bladder cancer is more common in whites than in blacks; however, blacks have a worse prognosis than whites.

Sex: The male-to-female ratio is 3:1. Women generally have a worse prognosis than men.

Age: The median age at diagnosis is 68 years, and the incidence increases with age.

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