bladder cancer (BC) is the 9th most commonly
diagnosed type of cancer in the world, with significant morbidity and mortality
1. It is a common urologic cancer that has the highest recurrence rate of any
malignancy and occurs mainly in older people. About 9 out of 10 people with
this cancer are over the age of 55 and the average age at the time of diagnosis
is 73. Overall, the chance for men of developing BC during their life is about
1:27, while for women, the risk is about 1:89. The American Cancer Society
estimates that in 2018 there will be 81,190 new cases of bladder cancer and
17,240 deaths in the United States 2.
The most important risk
factors for bladder cancer are environmental, such as tobacco smoking (smokers
are at least 3 times more likely to develop BC than nonsmokers) and workplace exposure
to industrial chemicals, for example aromatic amines and polycyclic aromatic
Numerous studies show that
bladder cancer is a heterogeneous disease characterized by different subtypes,
showing variable genetic landscape, clinical presentation (signs and symptoms),
possible treatment implications and prognosis. The most common type of bladder
cancer, which represents about the 90% of all the cases, is urothelial
carcinoma of the bladder (UCB), also
known as transitional cell carcinoma (TCC).
It begins in the transitional
epithelium that coats the inner surface of the bladder, composed of urothelial
cells which are able to change shape and stretch when the bladder is full.
Other types of bladder cancer include squamous cell carcinoma (cancer that
begins in the flat cells lining the bladder), adenocarcinoma (cancer that
begins in cells that produce and release fluids such as mucus) and small cell
carcinoma (cancer that begins in neuroendocrine cells).
bladder cancer (UCB) constitutes two distinct clinical phenotypes: the most
common (70% of newly diagnosed cases) is the non-muscle-invasive bladder cancer
(NMIBC), which grows into the lamina
propria and can generally be managed without surgical removal of the bladder. The
30% of disease cases are represented by the muscle-invasive bladder cancer (MIBC), which is associated with worse
outcomes, due to his growth in the bladder’s wall muscle and sometimes into the
fatty layers or surrounding tissue outside the bladder 3.