Article: Bladder cancer

Bladder cancer refers to any of several types of malignant growths of the urinary bladder. It is a disease in which abnormal cells multiply without control in the bladder. The bladder is a hollow, muscular organ that stores urine; it is located in the lower abdomen. The most common type of bladder cancer begins in cells lining the inside of the bladder (epithelial cells) and is called transitional cell carcinoma (TCC).

The greatest risk factor for bladder cancer is a genetic predisposition; it is also associated with smoking and occupational exposure to aniline-based dyes (such as in textile factories), as well as with petrol and other chemicals.

Signs and symptoms

Bladder cancer may cause blood in the urine, pain during urination, frequent urination, or feeling the need to urinate without results. These signs and symptoms are not specific to bladder cancer, and are also caused by noncancerous conditions, including prostate infections and cystitis.

Treatment

The treatment of bladder cancer depends on how deep the tumor invades into the bladder wall. Superficial tumors (those not entering the muscle layer) can be "shaved off" using an electrocautery device attached to a cystoscope. Immunotherapy in the form of BCG instillation is also used to treat and prevent the recurrance of superficial tumors. BCG immunotherapy is effective in up to 2/3 of the cases at this stage. Instillations of chemotherapy into the bladder can also be used to treat superficial disease.

Untreated, superficial tumors may gradually begin to infiltrate the muscular wall of the bladder. Tumors that infiltrate the bladder require more radical surgery where part or all of the bladder is removed (a cystectomy) and the urinary stream is diverted. In some cases, skilled surgeons can create a substitute bladder (a neobladder) from a segment of intestinal tissue, but this largely depends upon patient preference, renal function, and the site of the disease.

A combination of radiation and chemotherapy can also be used to treat invasive disease, and, in many cases, it is not yet known which is the better treatment - radiotherapy or radical ablative surgery.

Epidemiology

In the United States, bladder cancer is the fourth most common type of cancer in men and the ninth most common cancer in women. More than 47,000 men and 16,000 women are diagnosed with bladder cancer each year.

Genetics

The FGFR3, HRAS, RB1 and TP53 genes are associated with bladder cancer. As with most cancers, the exact causes of bladder cancer are not known; however, many risk factors are associated with this disease. Chief among them are smoking and exposure to industrial chemicals. Mutations in the FGFR3 gene that arise in the bladder are another important risk factor for developing bladder cancer. Similar changes in other genes, such as RB1, HRAS and TP53, may also increase risk. Each of these genes plays a critical role in regulating the cycle of cell division, preventing cells from dividing too rapidly or in an uncontrolled way. Alterations in these genes may help explain why some bladder cancers grow and spread more rapidly than others.

Bladder cancer is generally not inherited; tumors usually result from genetic mutations that occur in certain bladder cells during a person's lifetime. These noninherited genetic changes are called somatic mutations. A family history of bladder cancer is, however, a risk factor for the disease. Along these lines, some people appear to inherit a reduced ability to break down certain chemicals, which makes them more sensitive to the cancer-causing effects of tobacco smoke and certain industrial chemicals.