24/02/2014
What Is Prostate Cancer? What Causes Prostate Cancer?
Prostate cancer is a disease which only affects men. Cancer begins to grow in the prostate - a gland in the male reproductive system
What is the prostate?
The prostate is an exocrine gland of the male reproductive system, and exists directly under the bladder, in front of the re**um. An exocrine gland is one whose secretions end up outside the body e.g. prostate gland and sweat glands. It is approximately the size of a walnut.
The urethra - a tube that goes from the bladder to the end of the p***s and carries urine and semen out of the body - goes through the prostate.
There are thousands of tiny glands in the prostate - they all produce a fluid that forms part of the semen. This fluid also protects and nourishes the s***m. When a male has an or**sm the seminal-vesicles secrete a milky liquid in which the semen travels. The liquid is produced in the prostate gland, while the s***m is kept and produced in the testicles. When a male climaxes (has an or**sm) contractions force the prostate to secrete this fluid into the urethra and leave the body through the p***s.
Urine control
As the urethra goes through the prostate: the prostate gland is also involved in urine control (continence) with the use of prostate muscle fibers. These muscle fibers in the prostate contract and release, controlling the flow of urine flowing through the urethra.
The Prostate Produces Prostate-specific antigen (PSA)
The epithelial cells in the prostate gland produce a protein called PSA (prostate-specific antigen). The PSA helps keep the semen in its liquid state. Some of the PSA escapes into the bloodstream. We can measure a man's PSA levels by checking his blood. If a man's levels of PSA are high, it might be an indication of either prostate cancer or some kind of prostate condition.
prostate gland diagram
Diagram of the location of the prostate gland and nearby organs
It is a myth to think that a high blood-PSA level is harmful to you - it is not. High blood PSA levels are however an indication that something may be wrong in the prostate.
Male hormones affect the growth of the prostate, and also how much PSA the prostate produces. Medications aimed at altering male hormone levels may affect PSA blood levels. If male hormones are low during a male's growth and during his adulthood, his prostate gland will not grow to full size.
In some older men the prostate may continue to grow, especially the part that is around the urethra. This can make it more difficult for the man to pass urine as the growing prostate gland may be causing the urethra to collapse. When the prostate gland becomes too big in this way, the condition is called Benign Prostatic Hyperplasia (BPH). BPH is not cancer, but must be treated.
Prostate Cancer
In the vast majority of cases, the prostate cancer starts in the gland cells - this is called adenocarcinoma. In this article, prostate cancer refers just to adenocarcinoma.
Prostate cancer is mostly a very slow progressing disease. In fact, many men die of old age, without ever knowing they had prostate cancer - it is only when an autopsy is done that doctors know it was there. Several studies have indicated that perhaps about 80% of all men in their eighties had prostate cancer when they died, but nobody knew, not even the doctor.
Experts say that prostate cancer starts with tiny alterations in the shape and size of the prostate gland cells - Prostatic intraepithelial neoplasia (PIN). According to Medilexicon`s medical dictionary, Prostatic intraepithelial neoplasia means "dysplastic changes involving glands and ducts of the prostate that may be a precursor of adenocarcinoma; low grade (PIN 1), mild dysplasia with cell crowding, variation in nuclear size and shape, and irregular cell spacing; high grade (PIN 2 and 3), moderate to severe dysplasia with cell crowding, nucleomegaly and nucleolomegaly, and irregular cell spacing."
Doctors say that nearly 50% of all 50-year-old men have PIN. The cells are still in place - they do not seem to have moved elsewhere - but the changes can be seen under a microscope. Cancer cells would have moved into other parts of the prostate. Doctors describe these prostate gland cell changes as low-grade or high-grade; high grade is abnormal while low-grade is more-or-less normal.
Any patient who was found to have high-grade PIN after a prostate biopsy is at a significantly greater risk of having cancer cells in his prostate. Because of this, doctors will monitor him carefully and possibly carry out another biopsy later on.
Classification of prostate cancer
It is important to know the stage of the cancer, or how far it has spread. Knowing the cancer stage helps the doctor define prognosis - it also helps when selecting which therapies to use. The most common system today for determining this is the TNM (Tumor/Nodes/Metastases). This involves defining the size of the tumor, how many lymph nodes are involved, and whether there are any other metastases.
When defining with the TNM system, it is crucial to distinguish between cancers that are still restricted just to the prostate, and those that have spread elsewhere. Clinical T1 and T2 cancers are found only in the prostate, and nowhere else, while T3 and T4 have spread outside the prostate.
There are many ways to find out whether the cancer has spread. Computer tomography will check for spread inside the pelvis, bone scans will decide whether the cancer has spread to the bones, and endorectal coil magnetic resonance imaging will evaluate the prostatic capsule and the seminal vesicles.
