Bladder cancer

Definition

Bladder cancer is a malignant tumor within the bladder. In the United States, bladder cancers usually start from the cells lining the bladder (transitional cells).

These tumors may be classified based on their growth pattern:

• Papillary tumors have a wart-like appearance and are attached to a stalk.
• Nonpapillary tumors are much less common, but they are more invasive and have a poorer prognosis.

Alternative Names

Causes

As with most other cancers, the exact cause is uncertain. However, several factors may contribute to the development of bladder cancer.

Cigarette smoking increases the risk of developing bladder cancer by a factor of nearly five, compared to non-smokers. As many as 50% of all bladder cancers in men and 30% in women may be attributable to cigarette smoke. This risk does show a gradual decline in people who quit smoking.

About one in four cases of bladder cancer can be attributed to workplace exposure to carcinogens (cancer-causing chemicals). Arylamines are the chemicals most responsible. Dye workers, rubber workers, aluminum workers, leather workers, truck drivers, and pesticide applicators are at the highest risk, although arylamines have been reduced or eliminated in many workplaces.

The association between artificial sweeteners and bladder cancer has been studied and is weak or non-existent.

Women who received radiation therapy for the treatment of cervical cancer have an increased risk of developing transitional cell bladder cancer, as do some people who received the chemotherapy drug cyclophosphamide (Cytoxan).

A chronic (long term) bladder infection or irritation may lead to the development of squamous cell bladder cancer. However, this cancer is very slow growing. Bladder infections do not increase the risk of transitional cell cancers.

In third world countries, infection with a parasite (schistosomiasis) has been linked to the development of bladder cancer.

Bladder cancers are classified or staged based on their aggressiveness and the degree that they are different from the surrounding bladder tissue. There are several different ways to stage tumors. Recently, the TNM staging system has become common. This staging system contains several substages, but it basically categorizes tumors using the following scale:

• Stage 0 -- Non-invasive tumors limited to the bladder lining
• Stage I -- Tumor extends through the lining, but does not extend into the muscle layer
• Stage II -- Tumor invades the muscle layer
• Stage III -- Tumor extends past the muscle layer into tissue surrounding the bladder
• Stage IV -- Cancer has spread to regional lymph nodes or to distant sites (metastatic disease)

Bladder cancer spreads by extending into the nearby organs, including the prostate, uterus, vagina, ureters, and rectum. It can also spread to the pelvic lymph nodes or to other parts of the body, such as the liver, lungs and bones.

References

Walsh PC. Campbell's Urology. 8th ed. St. Louis, MO: WB Sanders; 2002:2732-2765. 

Herr HW. Surgical factors in the treatment of superficial and invasive bladder cancer. Urol Clin North Am. 2005; 32(2): 157-6.