December 14, 2021


In order to understand the different types of bladder cancer, you have to understand how the bladder is built. I like to describe the bladder sort of like installing a shag carpet. Imagine you’re installing a carpet in your home. There’s a hardwood floor under layer. Then there’s a carpet pad. And then there’s the actual carpet. The bladder wall, if you could cut through it and look at it sideways, has similar multi-layered structure to it. There’s the shiny smooth layer, sort of like the carpet, that touches the urine. That’s called mucosa. The carpet pad is a spongy layer called lamina propria. And the hardwood floor underneath is the actual muscle wall of the bladder itself that does the squeezing. Then on the outside of that, there’s a layer of insulating fat. Bladder cancers arise from the shiny smooth mucosa layer, which is in contact with the urine. There are two broad categories of bladder cancers. Ones that are just on the surface of the bladder. And when I say surface, this can be confusing. By surface, we mean the inside layer that touches the urine. And then there are bladder cancers that grow deeply into the wall of the bladder itself. Imagine a polyp or a growth on the surface layer of the bladder wall. Think of it like a bush, a plant, or a tree. For bladder cancers that are just on the surface, they have no roots that go deeply into the muscle wall. Those are called non-muscle invasive or surface bladder cancers. On the other hand, imagine a tree that’s growing from the wall of the bladder. The roots go deeply into the muscle layer. That’s called muscle invasive bladder cancer, and it has a much more serious prognosis. These two categories influence every aspect of bladder cancer care and diagnosis. Approximately 75% of bladder cancers are not muscle invasive, just on the surface. 25% are muscle invasive and require more advanced treatment options.