The diagnosis of prostate cancer can be made on clinical suspicion of the disease, following screening, or as an incidental finding during transurethral resection for suspected benign disease (TURP).
Clinically suspected prostate cancer
Prostate cancer can be completely asymptomatic or present with symptoms similar to benign prostatic enlargement (see symptoms). It can also present with the symptoms of metastatic disease.
On digital rectal examination prostate cancer feels rock hard and nodular. Invasion into the surrounding structures may be palpable as a hard mass. Spread to the lymph glands may be palpable in the groins or pelvis. Bony metastases to the lumbar spine or pelvis are often tender to palpation.
PSA (Prostate Specific Antigen) is a substance excreted by all prostate cells. The blood level of PSA is elevated in prostate cancer and the level of elevation correlates with the extent of disease. The PSA level can also be elevated by benign diseases such as prostatitis and benign prostatic hyperplasia. The normal range for PSA is 0 - 4 ng/ml. The higher the PSA the greater is the chance of having prostate cancer. Somebody with a PSA of 4 - 10 ng/ml has a 25% chance of having prostate cancer, while a PSA of greater than 10 carries a 50% risk of the disease. Very high levels of PSA (>100ng/ml) almost invariably indicate widespread metastatic disease.
The diagnosis of prostate cancer is confirmed by needle biopsy and histological analysis of the biopsy specimens. A transrectal ultrasound scan is performed via a probe inserted into the rectum, and ultrasound guided needle biopsies of the prostate are taken. The procedure is performed under local anaesthetic
All healthy men over the age of 50 years should have annual prostate cancer checks. Black men and men with a positive family history should start at age 40. The aim of screening is to diagnose the disease at an early stage while it is still potentially curable. By the time prostate cancer becomes symptomatic it is usually beyond cure. The screening tests consist of a digital rectal examination and a PSA blood test. The prostate gland may feel entirely normal despite the presence of an early cancer. The combination of PSA and digital rectal examination is more sensitive than either test alone. If one or both of these tests are abnormal a transrectal ultrasound and needle biopsies of the prostate gland are performed.
Incidental finding following TURP
Whenever a transurethral resection of the prostate gland is performed for suspected benign disease the removed tissue is sent for histological analysis. Occasionally evidence of unsuspected prostate cancer is found in the tissue. In a young man with an otherwise long life expectancy this is obviously significant. A tiny focus of cancer in an elderly man is probably not significant, since the prostate cancer will not have sufficient time to become bothersome.