The bladder is an expandable,
hollow organ in the pelvis that stores urine (the
body’s liquid waste) before it leaves the
body during urination. The urinary tract is made
up of the kidneys, ureters, bladder, and urethra
and is lined with a layer of cells called the
urothelium. This layer of cells is separated from
the muscularis propria (bladder muscles) by the
lamina propria (a thin, fibrous band).
Bladder cancer is a cancerous tumor that begins
when cells in the bladder become abnormal and
grow uncontrollably, forming a mass of tissue.
It is described as either noninvasive or invasive.
Noninvasive cancer does not spread through the
lamina propria, and invasive cancer can spread
through the lamina propria. Noninvasive cancer
may also be called superficial cancer, although
that term is being used less often because it
may incorrectly imply that this type of cancer
is not serious. Invasive cancer is subdivided
as either cancer that only grows into the lamina
propria or cancer that grows into the muscle
There are three main types of bladder
cancer, depending on the type of cell where
the cancer begins:
Urothelial carcinoma: Urothelial
carcinoma is a new term for this type of bladder
cancer. It was previously called transitional
cell carcinoma or TCC. Urothelial carcinoma
accounts for about 90% of all bladder cancers
and begins in the urothelium. A tumor of this
type may be described further using one of the
four subcategories explained below.
carcinoma: This subtype of urothelial
carcinoma is limited to the urothelium and is
noninvasive. It may spread into the lamina propria
beneath the transitional cells. This is sometimes
called invasive, though it is not the deeply
invasive type that can spread to the muscle
Deeply invasive urothelial carcinoma (often
called invasive urothelial carcinoma). This
subtype of urothelial carcinoma spreads to the
bladder's muscularis propria and sometimes to
the fatty layers or surrounding tissue outside
Papillary urothelial carcinoma: Papillary
is a word that describes a growth that is like
a small polyp or flower-shaped cluster of cancer
cells. A noninvasive papillary tumor grows into
the hollow center of the bladder on a stalk.
Invasive papillary urothelial carcinoma can
spread into the muscle layer.
Flat urothelial carcinoma:
Noninvasive flat urothelial carcinoma (also
called carcinoma in situ, or CIS) grows in the
layer of cells closest to the inside of the
bladder and appears as flat lesions on the inside
surface of the bladder. Invasive flat urothelial
carcinoma may invade the deeper layers of the
bladder, particularly the muscle layer.
Squamous cell carcinoma: This
type accounts for about 4% of all bladder cancers
and starts in squamous cells, which are thin,
Adenocarcinoma: This type
accounts for about 2% of all bladder cancers
and begins in glandular cells.
All three major types of bladder cancer can
metastasize (spread) beyond the bladder. If
the tumor has spread into the surrounding organs
(the uterus and vagina in women, the prostate
in men, and/or nearby muscles), it is called
locally advanced disease. The area outside of
these organs where bladder cancer usually spreads
is the lymph nodes in the pelvis. If it has
spread into the liver, bones, lungs, or other
parts of the body, these are distant metastases
and the cancer may be called advanced disease.
There are other, less common types of cancer
that arise in the bladder, including sarcoma
(which begins in the muscle layers of the bladder)
and small cell anaplastic cancer (a rare type
of bladder cancer that is likely to spread to
other parts of the body).