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Bladder Cancer

Overview


Anatomy and Physiology of the Bladder

The bladder is a sac-like organ in the pelvis that stores the urine produced by the kidneys. There are two tubular structures called ureters (one from each kidney) that drain the urine into the bladder. The urethra is the outflow tract of the bladder and connects the bladder to the exterior.
Anatomically, the bladder is the most anterior (closest to the front) organ in the pelvis, located just behind the pelvic bone. Organs closest to the bladder include the rectum (the last part of the colon), which is the most posterior (closest to the back) organ in the pelvis, the prostate gland and seminal vesicles (in males), and the uterus, ovaries and fallopian tubes (in females). In males, the prostate gland and seminal vesicles (organs that contribute secretions in semen) are situated below the bladder and in front of the rectum. In females, the uterus (the womb), ovaries and fallopian tubes are located posterior the bladder and anterior to the rectum.
The bladder itself is made up of four layers. These layers are important landmarks in determining how deeply the tumor has invaded and the ultimate stage of the cancer.

1.    Epithelium: The epithelium, which lines the bladder and is in contact with the urine, is referred as transitional epithelium or urothelium. Most bladder cancers originate from the cells of this transitional epithelium. The urethra, ureters and the pelvis of the kidney are also lined by this transitional epithelium, therefore, the same types of cancers seen in the bladder can also occur in these sites.
2.    Lamina propria: Under the epithelium is the lamina propria, a layer of connective tissue and blood vessels. Within the lamina propria, there is a thin and often discontinuous layer of smooth muscle called the muscularis mucosae. This superficial layer of smooth muscle is not to be confused with the true muscular layer of the bladder called the muscularis propria or detrusor muscle.
3.    Muscularis propria or detrusor muscle: This deep muscle layer consists of thick smooth muscle bundles that form the wall of the bladder. For purposes of staging bladder cancer, the muscularis propria has been divided into a superficial (inner) half and a deep (outer) half.
4.    Perivesical soft tissue: This outermost layer consists of fat, fibrous tissue and blood vessels. When the tumor reaches this layer, it is considered out of the bladder.

There are several types of bladder cancers: the major type is urotheloal (transitional cell) carcinoma (>90%); other types include squamous cell carcinoma (2%); and adenocarcinoma (1%).

Grade and Stage describe the bladder tumor, helping to provide
guidance for the urologist in choosing the best treatment option(s). Staging
is a careful attempt to find out the extent of the cancer. Staging will define
whether the cancer has invaded into or through the bladder wall, whether
the disease has spread, and if so, to what parts of the body. The higher the
stage the further the cancer has grown away from its original site on the
surface of the bladder.

The following are the stages for bladder tumors: (Figure 5)
T0: No tumor
Ta: Papillary tumor involves the urothelium without invasion
into the bladder wall
TIS (CIS): Carcinoma in situ (non-invasive flat high grade cancer)
T1: Tumor invades the lamina propria
T2: Tumor invades the muscle layer
T3: Tumor grows through the bladder wall into the
surrounding fat layer
T4 Tumor invades other organs near the bladder
(i.e., prostate, uterus, vagina, pelvic wall)

Grade refers to what the cancer cells look like, and how many cells are multiplying.  Grade is separated into low and high grade.  High grade cancers are more aggressive.

The tumor can grow into the surrounding organs (uterus and vagina in women and prostate in men) and that is called locally advanced disease. It can also spread to the lymph nodes and/or to the liver, bones, or lungs and that is called distant metastasis. Rarely bladder cancer spreads to other parts of the body.

Epidemiology
    

  • Bladder cancer is nearly three times more common in men in the United States than in women, but women have more than a 30% higher chance of dying of bladder cancer, if they develop it, than men do.
  • Bladder cancer is rare in persos younger than the age of 50, with median ages at diagnosis of around 70 years for each gender. Incidence of and mortality from the disease increase further with age.
  • Bladder cancer occurs roughly half as often in African Americans as in whites ut is nearly twice as likely to be lethal in African Americans as in whites.
  • In Hispanic Americans, bladder cancer also occurs about half as often as in whites but Hispanics are less likely to die of bladder cancer, if they develop it, than whis are.

 



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