What are the different types of bladder cancer?

Bladder cancer can be divided into two main types: primary and metastatic. Primary bladder cancer refers to cancer that begins in the bladder, while metastatic bladder cancer refers to cancer that begins in another organ or tissue and spreads to the bladder. Cancers in other organs can spread to the bladder directly through the blood, lymphatic system, or from nearby organs such as the prostate or cervix.

Primary bladder cancer is much more common than metastatic bladder cancer. There are several types of primary bladder cancer, with the previously mentioned transitional cell carcinoma accounting for more than 90% of bladder cancers. Transitional cell carcinomas can be: ① Papillary carcinomas, which look like cauliflower and are attached to the bladder wall by a short pedicle; ② Sessile carcinomas, which appear flat, have no pedicle, and have a wide base; ② Mixed carcinomas, which have both of these characteristics. About 70% of transitional cell carcinomas are papillary, and generally have a better prognosis than sessile ones. Less common bladder cancers include squamous cell carcinoma, adenocarcinoma, and urachal carcinoma.

In the United States, squamous cell carcinoma accounts for 3% to 7% of all bladder cancers. In Egypt, the proportion can be as high as 75%. In Egypt, there is a very common parasitic infection called schistosomiasis, which can easily lead to squamous cell carcinoma of the bladder. It is generally believed that the infection causes long-term chronic irritation of the bladder, which leads to squamous cell carcinoma. Other factors that cause chronic irritation, such as long-term indwelling urinary catheters, can also induce squamous cell carcinoma. Squamous cell carcinoma tends to metastasize to adjacent tissues by direct invasion, and generally does not metastasize to the lymph nodes like transitional cell carcinoma. Because it is more locally invasive and relatively insensitive to chemotherapy and radiation therapy, the prognosis is worse than that of transitional cell carcinoma.

Bladder adenocarcinoma is quite rare, accounting for only about 2% of bladder cancers in the United States. This tumor is also associated with chronic irritation. The tumor tends to be high grade, highly aggressive, and generally has a poor prognosis.