The most common type of bladder cancer is "transistional cell" or urethelial cancer. This arises in the urethelial tissue is, very basically, the tissue that forms the lining of the bladder and adjacent structures such as the ureters. It is the type of cancer that most of us have.
I am very sorry to hear about your diagnosis. Please let us know what the oncologist recommends. This might be a good time to consider getting an opinion at a center that has major expertise in this type of cancer, if you aren't already being treated at one. There is a "treatment center finder"
bladdercancersupport.org/bladder-cancer-help/resources/treatment-center-finder
here on our web page with lots of places listed geographically. You want to be treated by doctors who have lots of experience with urothelial cancer.
We will be thinking good thoughts for you.
Sara Anne