Prostate Cancer (cont.)
Why is Prostate Cancer Screening Important?
Although currently controversial, most urologists would recommend regular screening for prostate cancer using PSA and DRE in men who are likely to live more than 10 years (for example, life expectancy >10 years).
- Elevated prostate serum antigen (PSA): Although the PSA test is not useful to actually diagnose prostate cancer, it predicts the risk of prostate cancer being present. Currently, most prostate cancers are discovered when a prostate biopsy is performed after a raised serum prostate specific antigen (PSA) blood test is detected. A PSA test is usually performed as a part of a health screening program. However, its use as a screening method is controversial as there is no universally accepted threshold above which the PSA is considered abnormal. Raising the threshold value reduces the number of unnecessary biopsies, but increases the number of cancers that are missed. Lowering the threshold value reduces the number of cancers that are missed, but may lead to the detection of more cancers that will never become clinically significant.
- Abnormal digital rectal exam (DRE): Prostate cancers may be suspected with an abnormal prostate exam detected by digital rectal exam (DRE). A digital rectal exam is part of a thorough regular health examination. During DRE, the examiner inserts a gloved and lubricated finger (“digital” refers to finger) in the rectum to feel the back of the prostate for abnormalities. The exam may reveal asymmetry, swelling, tenderness, nodules, or irregular areas in the prostate. In contrast, symmetric enlargement and firmness of the prostate are more frequently seen in men with benign prostatic hyperplasia (BPH). A suspicious prostate exam prompts the physician to request a prostate biopsy to confirm or rule out the presence of prostate cancer (details regarding PSA and prostate biopsy are available in subsequent sections). This finger exam cannot detect all tumors of the prostate gland. About 25% to 30% of prostate tumors are located in areas of the gland that cannot be felt during digital rectal examination. Prostate cancer is found in approximately 30% of men with suspicious prostate examination.
- Elevated prostate cancer antigen 3 (PCA3): PCA3 is new test that may help to discriminate between cancer-related versus nonspecific PSA elevations. There is not enough data to determine if PCA3 is useful for prostate cancer screening, but it may help to determine the need for biopsy. Measuring PCA3 is done using a urine sample after a prostate massage.
- Screening is used for the detection of prostate cancer in men from the general population with no related symptoms. The purpose of screening is to detect and treat the disease earlier in order to reduce prostate cancer mortality.
- The decision to screen is a shared decision between the patient and the physician.
- The physician should discuss the benefits, risks, and limitations of prostate cancer screening with patients and then offer testing.
- The American Urological Association (AUA) issued their latest guidelines for prostate cancer in 2013. According to these guidelines, men at the age of 55-69 should be offered a baseline serum PSA test and a prostate exam (DRE) to ascertain the risk of prostate cancer. Subsequent screening and tests may be performed according to the findings on this initial evaluation and an individual's risk of getting the disease on the basis of other factors such as race, ethnicity, and family history of prostate cancer. Most urologists currently would advise some form of screening in men with life expectancy greater than 10 years. Most frequently, it would be performed on an annual basis.
- There is no universally accepted age limit after which screening should be stopped. AUA guidelines recommend that the decision on whether to screen in men age >75 years should be made on an individual basis.
Urologists and Oncologists Perform Prostate Cancer Evaluation and Diagnosis
Medical interview and physical examination:
A proper medical interview eliciting a thorough medical history and a physical examination are essential in the diagnostic workup of any man in whom prostate cancer is suspected. He may be referred to a physician who specializes in urinary tract diseases (a urologist) or in urinary tract cancers (a urologic oncologist). A man will be asked questions about his medical and surgical history, lifestyle and habits, and any medications he takes. Risk factors including family history of prostate cancer will be assessed (see prostate cancer risk factors).
Digital rectal examination (DRE) is part of the physical examination: All men with firm swelling, asymmetry, or palpable, discrete, firm areas or nodules in the prostate gland require further diagnostic studies to rule out prostate cancer, particularly if they are over the age of 45 or have other risk factors for the disease (see risk factors of prostate cancer).
Because urological symptoms (see prostate cancer symptoms) can indicate a variety of conditions, a man may undergo further testing to pinpoint their cause. Initial screening tests include blood testing for PSA and urine testing for blood or signs of infection.
Prostate specific antigen (PSA):
PSA is an enzyme produced by both normal and abnormal prostate tissues. It may be elevated in noncancerous conditions, such as prostatitis (inflammation of the prostate) and benign prostatic hypertrophy (noncancerous enlargement of the prostate), as well as in cancer of the prostate. Therefore, confirmation of an elevated serum PSA is advisable prior to proceeding to prostate biopsy.
PSA values over time may also be more helpful for monitoring recurrence of cancer and the response to treatment than in diagnosing a previously unknown cancer.
The following standards have been set for PSA levels:
- Less than 4 ng/mL: Normal value. The management of men with lower PSA elevations (<4 ng/mL) is less clear since most will have negative biopsies. However, a substantial number of men with prostate cancer do have a serum PSA concentration less than 4 ng/mL.
- 4 to 10 ng/mL: Prostate biopsy is usually recommended for men with a total serum PSA between 4 to 10 ng/mL, regardless of the digital rectal examination findings, in order to increase the chances of diagnosing disease while it is organ-confined. In men with PSA in this range, approximately one in five biopsies will reveal cancer.
- Greater than 10 ng/mL: Prostate biopsy is strongly recommended. Although the chance of finding prostate cancer is over 50 percent, benign prostatic disease does produce a marked increase in serum PSA in some men.
- Less than 0.2 ng/mL: After the prostate is surgically removed.
Traditionally, a PSA of 4 ng/mL has been used as a cutoff value for deciding for or against doing a prostate biopsy. However, some experts now recommend lowering that to 2.5 ng/mL and performing the biopsy in men who have levels in excess of this threshold. The American Urological Association guidelines (2009) do not define a definite cutoff point but advise that all the other risk factors for prostate cancer be taken into account while making a decision on whether to proceed for a biopsy. One of the important factors that needs to be considered is the rate at which the PSA value has increased over time on repeated measurements (referred to as the PSA velocity).
Based upon the symptoms, physical examination, DRE and PSA level, further blood tests may include:
- Complete blood cell count (CBC): The relative amounts of different blood cells are checked. Anemia is a common sequel to cancers, as are certain other blood irregularities.
- Alkaline phosphatase: This enzyme is found in the liver and in bone. It is a sensitive indicator of both liver and bone abnormalities including cancer spread to these areas.
- BUN and creatinine: These measures are used to assess how well the kidneys are working. Levels can be elevated in a number of conditions (such as kidney failure) and may suggest an obstruction or blockage in the urinary system.
Medically Reviewed by a Doctor on 11/22/2016
Pierre-Alain Hueber, MD, PhD
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