How is prostate cancer diagnosed?
Before the discovery of prostate specific antigen (PSA), prostate cancer is
usually diagnosed by physical examination. Physical examination (digital rectal
examination) typically reveals an induration or nodularity of the prostate.
Nodules of the prostate cancer are generally hard and painless. Patients with
advanced prostate cancer may also present with bony pain (from bony metastases)
and/or inguinal lymph adenopathy.
PSA is a protein that serves as a tumor marker unique to the prostate gland. PSA
test significantly increases the yield of digital rectal examination in the
diagnosis of prostate cancer. PSA blood test can detect prostate cancer of very
low volume and is used in initial diagnosis and diagnosis of recurrent disease
after treatment. PSA is relatively sensitive and specific for the screening of
prostate cancer, but it should be used with physical examination and other
imaging studies, such as transrectal ultrasound (TRUS), for the diagnosis of the
disease.
The standard method to diagnose prostate cancer is a true-cut prostate biopsy
after a positive serum PSA test or DRE. The procedure is generally guided by
TRUS. Your Urologist generally obtains six pieces of tissue by sampling the
apex, midportion, and the base of both side of the prostate gland. Biopsy
specimens are sent to pathology for further confirmation of the diagnosis.
Occasionally, patient is diagnosed with prostate cancer during trans-urethral
resection of the prostate (TURP) procedure for their benign prostatic
hypertrophy (BPH). Patients with incidental finding of prostate during TURP are
staged as early T1 diseases. These patients generally have favorable prognosis
after treatment.
After the pathological confirmation of the diagnosis, your urologist may order
further imaging studies to assess the extent of the cancer. A bone scan is very
sensitive for detecting bony metastases from prostate cancer in patients with
high serum PSA level or bony pain. Routine use of bone scan for staging is not
encouraged because the probability of a positive bone scan is very low if the
patients' PSA level is less than 20 ng/mL and have no symptoms of bony
metastases.
CT scans and MRI are used to evaluate the extent of prostate cancer in the
pelvis. They are usually used to detect the lymph adenopathy in the pelvis and
low abdomen. However, these studies have not been shown to increase the
prognosis of a patient, and they are not routinely used in early staged
patients.
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