Prostate cancer

Prostate cancer, usually refers to prostate
adenocarcinoma, where adeno- means gland and carcinoma refers to uncontrolled growth of
cells – so prostate cancer is a tumor or growth that originates in the prostate gland.

 Only males are born with a prostate, so this
condition only affects males and not females. Typically, when there’s a prostate cancer
it’s considered malignant, meaning thatthe tumor cells can metastasize, or invade
and destroy surrounding tissues as well astissues throughout the body. The prostate is a small gland, about the size
and shape of a walnut, that sits under thebladder and in front of the rectum. The urethra which is the tube through which
urine leaves the bladder, goes through theprostate before reaching the penis. And that part of the urethra is called the
prostatic urethra. The prostate is covered by a capsule of tough
connective tissue and smooth muscle. Beneath this layer, the prostate can be divided
into a few zones. The peripheral zone, which is the outermost
posterior section, is the largest of the zoneand contain about 70% of the prostate’s
glandular tissue. Moving inward, the next section is the central
zone which contains about 25% of the glandulartissue as well as the ejaculatory ducts that
join with the prostatic urethra. Last, is the transitional zone, which contains
around 5% of the glandular tissue as wellas a portion of the prostatic urethra. The transitional zone gets its name because
it contains transitional cells which are alsofound in the bladder. The transitional zone undergoes hyperplasia,
or an increase in the number of cells, ina large percentage of older men, and that
often leads to compression of the urethra. This is called benign prostatic hyperplasia
and is often considered a normal part of aging. At the microscopic level, each of the tiny
glands that make up the prostate is surroundedby a basement membrane made largely of collagen. Sitting within that basement membrane, is
a ring of cube-shaped basal cells as wellas a few neuroendocrine cells interspersed
throughout. Finally, there’s an inner ring of luminal
columnar cells, which are within the lumenor center of the gland. Luminal cells secrete substances into the
prostatic fluid, that make it slightly alkalinethat give it nutrients which nourish the sperm
and help it survive in the acidic environmentof the vagina. During an ejaculation, sperm leave the testes,
travel through the vas deferens, into theejaculatory ducts, and travel through the
prostatic urethra. Smooth muscles in the prostate contract and
push the prostatic fluid into the urethrawhere it joins the sperm as well as the semen
which is the fluid that comes from the seminalvesicles. The luminal cells also produce prostate specific
antigen, or PSA, which helps to liquefy thegel-like semen after ejaculation, thereby
freeing the sperm to swim. The basal cells and luminal cells of the prostate
rely on stimulation from androgens, or malesex hormones, for survival. The androgens include testosterone, which
is produced by the testicles, androstenedioneand dehydroepiandrosterone which are produced
by the adrenal glands, and dihydrotestosterone,which is made from testosterone by the prostate
itself. Without these androgens, the normal prostate
cells, particularly the luminal cells, cannotsurvive, and undergo apoptosis or programmed
cell death. For example, if the testicles are castrated,
or removed for some reason, the prostate significantlyshrinks in size, largely due to death of the
luminal cells. Prostate adenocarcinoma most often results
from a genetic mutation in a luminal cell,but can also be a basal cell, and it results
in that cell dividing uncontrollably. Some risk factors for a genetic mutation include
old age, obesity, and a high fat-low fiberdiet. Mutations in two genes that have been linked
specifically to prostate cancer are breastcancer gene 1 and breast cancer gene 2, also
known as BRCA1 and BRCA2 – both of which alsocause breast cancer. Once a cancer-causing mutation occurs within
a cell, the affected cell begins to grow andreplicate out of control, forming a tumor. Early on, prostate cancer cells depend heavily
on androgens for survival, but eventually,the cancer cells mutate and find a way to
keep multiplying without relying on androgens. Overall, prostate cancer cells have a relatively
slow rate of growth compared to other typesof cancers. Finally, even though prostate adenocarcinoma
is the most common type of prostate cancer,other rare types exist as well. These typically arise from other cell types
in the prostate, for example transitionalcell carcinoma arises from cells in the transitional
zone, and small cell prostate cancer arisesfrom neuroendocrine cells. Early on, prostate cancer typically causes
no symptoms. That’s because the majority of prostate
cancers arise in the posterior peripheralzone, which is far away from the urethra. As a result, these tumors can grow quite large
before they cause problems with urination. Over time, if the cancer does compress or
invade the urethra or bladder, it can causedifficulty urinating, bleeding, and pain with
urination and ejaculation. If the cancer becomes metastatic, it most
commonly spreads to the bones, like the vertebraeor pelvis, resulting in hip or lower back
pain. Prostate cancer can be detected by a digital
rectal examination, which is where a finger,is inserted into the rectum to feel against
the anterior wall of the rectum which liesalong the posterior part of the prostate. A tumor located here would feel like an irregularly
hard lump. But if the tumor arises elsewhere, like in
the anterior peripheral zone, then the tumorwould be out of reach during the digital rectal
exam. Another approach is to use a transrectal ultrasound
or MRI to image the prostate. Prostate cancer can also cause an elevation
in the prostate specific antigen. But ultimately, the diagnosis of prostate
cancer requires a biopsy, so that the cellscan be scored using the Gleason grading system. The Gleason scale identifies the two most
common cell patterns within the prostate tissueand assigns a score between one and five to
both of them. A score of 1 represents normal, well differentiated
cells, and a score of 5 represents highlyabnormal cells that barely resemble the normal
prostate tissue. Once the primary and secondary patterns have
each received a score from one to five, thesetwo numbers are added together, resulting
in a total Gleason score between two and 10with two representing low-grade tumors and
10 representing high-grade, dangerous tumors. In terms of treatment, when the tumor is confined
to the prostate, and hasn’t metastasized,active surveillance is usually done. This includes routine tumor marker measurement
as well as imaging, to ensure that the prostatecancer remains confined to the prostate. If the tumor spreads beyond that point, treatment
options include surgery, radiation therapy,chemotherapy, and hormonal therapy. Alright, as a quick recap… prostate cancer
usually refers to prostate adenocarcinoma,but can also include more rare types of tumors
as well. It typically begins in the posterior peripheral
zone of the prostate and can be detected usinga digital rectal examination. Typically, a serum prostate specific antigen
is also elevated in prostate cancer. Treatment may include chemotherapy, radiation
therapy, surgery, and hormonal therapy, butactive surveillance is also an option in many
cases where it’s localized to the prostate.