The prostate is a secondary sexual organ found in all male mammals.
In the human, the prostate is a single, fused, midline structure wrapped around the urethra. The prostate and seminal vesicles produce the liquid portion of semen and are thought to be required for fertility.
The position of the prostate complicates surgical access. The pointed prostatic apex lies in the bottom of the pelvic cavity, where it attaches to the urethra. The back of prostatic surface rests against the rectum. The wide prostatic base rests against the bladder neck.. Behind the prostate and seminal vesicles is the thick Denonvillier's fascia. Resting over all these structures is the bladder, behind which are the ureters.

Prostatitis, an inflammation of the prostate, is seen in relatively young men. Benign enlargement of the prostate (BPH) increases in incidence as men age. BPH is sometimes associated with frequent urination, weak urinary stream, night-time urination, and other symptoms. Cancer is common in the prostate and also increases in incidence as men age.

PSA (prostate-specific antigen) is a protein produced by the cells of the prostate. PSA is found in very high concentrations in the ejaculate and only a small portion leaks into the bloodstream. The concentration of PSA in the blood provides an estimate of the risk of having prostate cancer. This is the reason for measuring PSA in asymptomatic men. PSA concentration between 2.5 and 10.0 ng/ml is associated with a probability cancer on a biopsy of approximately 25%. Like any test, PSA must be interpreted in context, as infections, medications, and other factors can cause fluctuations in the blood concentrations. PSA is not a diagnostic test. To diagnose prostate cancer today requires a biopsy. ALL MEN ABOVE 50 YEARS OF AGE SHOULD GET PSA DONE.
In doubtful cases, free PSA estimation is done and its % in relation to total PSA is calculated. Less than 10% is strong indicator of cancer.
All men over 50 years should get PSA done every year

Is enlarged prostate cancerous?

No. The more common enlargement of prostate is non cancerous.

Yes, the cancer develops in outer part of prostate which is not removed in surgery of BPH. That's why, PSA estimation is still important once a year.

Once suspected, urologist does prostatic biopsy. This is done under ultrasound guidance using an biopsy gun. Depending upon the size, upto 12 biopsies may be done. If the cancer is palpable, it can be done without ultrasound also. The procedure is done under local anesthesia and under antibiotic cover. One must stop blood thinners like aspirin 3-5 days before biopsy. There are insignificant incidence of fever, blood in urine or in stools.

.Grade is a description of the cancer cells as they appear under a microscope and is assigned by a pathologist. Gleason grading system is the main system. This shows the aggressiveness of the tumor. Stage is the extent of a cancer and is assessed by various means, such as physical examination and bone scans. Prostate cancer is staged commonly with the TNM system. T represents the size of the primary tumor in the prostate. N represents the involvement of lymph nodes. M represents metastasis to distant sites, e.g. bones.