superficial tumors (carcinoma in situ , or Tis) or muscle invasive tumors. Muscle invasive cancers may go through a Tis phase or may develop independently, so even though Tis does not invade muscle, the potential for invasion is implied. More important, Tis tends to recur again and again. Tis tumors, therefore, indicate an unstable, or sick, bladder lining.
How It Spreads Tumors can grow through the bladder muscle directly into the surrounding fat (perivesical) and into adjacent structures such as the prostate, vagina, rectum, uterus and pelvic bone. They also can directly enter the small blood and lymph vessels that supply the normal bladder wall. When they do, they can spread to local lymph nodes in the pelvis and farther up in the abdomen or be carried by the bloodstream to the lungs, bone and liver.
What Causes It Most of the time we are unaware of exposure to potent bladder carcinogens in our food and water supply, but some materials and the industries that use them have been strongly implicated with an increased risk for development of bladder cancer.
Bladder carcinogens include benzidine, bracken fern (sometimes used in salads), naphthylamines and aromatic amines, nitrosamines, some cancer therapy drugs (cyclophosphamide, melphalan), local radiation therapy , various dyes and solvents, chronic abuse of some pain medications such as phenacetin and acetaminophen, and particularly smoking cigarettes.
