Whether bladder cancer is superficial or invasive, it must still be confined to the bladder to be treated successfully by surgery. Once the tumor escapes from the bladder, it is difficult or impossible to remove the tumor completely. Like any other cancer, bladder cancer has three different routes by which it can escape the confines of the bladder. These three are (1) direct extension, (2) lymphatic spread, and (3) vascular spread.
1. Direct extension: As the tumor grows, it may gradually extend through each layer of the bladder wall. Once it has grown through the entire bladder wall, it may continue to grow directly into an adjacent structure, such as the rectum, prostate, vagina, or uterus. When your doctor performs a rectal exam, he or she is checking for this type of growth. By pushing on your abdomen at the same time, he or she can deter-mine the extent of the spread. Women with bladder cancer should also have a pelvic exam as part of the evaluation to check for growth into the vagina or uterus. If the tumor has invaded into adjacent organs, then surgery will not often be curative, and your doctor may recommend alternative treatments. The amount of extension is assessed by a combination of the tumor biopsy, physical exam, and a CT scan.
2. Lymphatic spread: This is usually the first way in which bladder cancer spreads. In addition to blood vessels, the body has a second network of channels to collect fluid. This is called the lymphatic system. The main job of this system is to carry fluid and cells back to the bloodstream. The lymphatic channels carry the fluid to the lymph nodes. These lymph nodes play an important role in your immune system, but they also give tumor cells fertile islands on which to grow. The natural environment of these islands provides everything a tumor cell needs to prosper. Once a node has been seeded with tumor cells, it will enlarge and can eventually obstruct the flow of lymph. Most importantly, it signals us that the tumor has spread outside of the bladder, which will influence the types of treatment your doctor can offer you. Many urologists feel that removal of all the lymph nodes with cancer in them can improve long-term survival in these patients. If you are having surgery, discuss with your doctor how extensive the lymph node part of the surgery will be.
3. Vascular (bloodstream) spread: If the tumor grows into a blood vessel, then cells can be swept into the bloodstream. They will circulate in the blood until they die, are removed by your immune system, or land in another organ and begin to grow. The most common locations for blood-borne bladder cancer cells to land are the liver (38%), lung (36%), bone (27%), adrenal glands (21%), and intestine (13%). Less commonly, it may spread to the other organs. Squamous cell cancers are the most likely to go to the bones.