The American Cancer Society (ACS) states that men should “make informed decisions with their doctor about whether to be tested” for prostate cancer. This is due to the lack of research to prove that the potential benefits of screening outweigh the harms of testing and treatment. The ACS recommends that men who are 50 years of age or older should discuss the pros and cons of screening with their doctors. Those at a higher risk of prostate cancer—such as African-American men or men with a family history of prostate cancer—should start the discussion with their doctors at age 45.
Most prostate cancer tests are part of the diagnostic process. However, some tests are used after a diagnosis is made to determine how extensive the cancer is and how much it has spread through the body (metastasized).
Prostate-Specific Antigen (PSA) Blood Test
Prostate-specific antigen (PSA) is a protein made in the prostate. It is elevated in several disease states, including urinary tract infection, benign prostatic hypertrophy (BPH), and instrumentation of the urological tract. However, elevations in PSA have been shown to correlate with prostate cancer, so screening for PSA levels is a valuable tool for detecting prostate cancer. Epidemiologic studies have demonstrated significant declines in prostate cancer mortality rates coincident with the introduction of widespread PSA-based screening.
PSA Levels: What Do They Mean?
A PSA level of less than 4 nanograms per milliliter (ng/ml) is considered normal, between 4 and 10 is borderline, and above 10 is high. High PSA levels may be due to prostate cancer but can also indicate prostatitis (inflammation of the prostate) or benign prostatic hyperplasia (BPH, also called an enlarged prostate), which are two very common noncancerous conditions. If a PSA test yields abnormal results, more tests must be done to determine if prostate cancer is present. PSA tests are also used after a positive diagnosis of prostate cancer to track the cancer’s growth and measure the effectiveness of treatments.
PSA Test Controversy
Many prostate cancers are slow growing and occur in elderly men, and those who are likely to develop other diseases that are a more significant threat to their health. As such, there is some controversy over whether an elevated PSA results in unnecessary interventions that may not be an overall threat to a patient’s well-being. Some advocacy groups recommend regular screenings for men as young as age 40, whereas others do not recommend these tests at all unless there is a strong family history of or other risk factors for prostate cancer. However, very strong evidence is now available that PSA-based screening reduces both the rate of metastatic disease and prostate cancer-specific mortality, and the leading healthcare organizations recommend PSA screening.
Digital Rectal Exam (DRE)
During a digital rectal exam (DRE), a doctor inserts a gloved, lubricated finger into the rectum to feel the prostate for lumps, hard spots, or other abnormalities. This exam can help distinguish between benign prostatic hyperplasia (BPH) and prostate cancer, but it is unable to detect the earliest stages of cancer, when tumors are too small to be felt.
A biopsy is a minor surgical procedure during which a sample of tissue is taken from the body for further study. If a prostate-specific antigen (PSA) test or digital rectal exam (DRE) indicates abnormalities, a prostate biopsy is almost always the next step. In a prostate biopsy, a doctor inserts a small needle into the prostate, either through the rectum or the perineum (the area between the rectum and the scrotum) and removes small samples of tissue.
Biopsies are often done in conjunction with transrectal ultrasound, during which an ultrasound probe is inserted into the rectum to help guide needle placement. A prostate biopsy procedure takes about 15 minutes, and it is usually done with no anesthesia or only local anesthesia to numb the area where the needle is inserted.
Possible Biopsy Results
After the biopsy, a pathologist examines the collected cells under a microscope to look for irregularities. If cancerous tissue is found, it is assigned a Gleason score—between 2 and 10—based on how abnormal the cells look. The higher the Gleason score, the more likely the cancer is to spread to other areas of the body.
A prostate biopsy can also diagnose other cell abnormalities that are not themselves cancer but can indicate a high risk of cancer, including prostatic intraepithelial neoplasia (PIN) and atypical small acinar proliferation (ASAP). There are two types of PIN—low-grade and high-grade. Low-grade PIN is not associated with prostate cancer, but 20 to 30 percent of men with high-grade PIN also have prostate cancer. And 40 to 50 percent of men with ASAP also have prostate cancer.
After prostate cancer is diagnosed, a number of tests are used to determine how severe the cancer is and whether it has spread to other areas of the body.
Computed Tomography (CT or CAT) Scan
X-rays are used to take a three dimensional picture of tissues and organs inside the body, which is then examined for signs of tumors.
Magnetic Resonance Imaging (MRI)
Magnetic fields are used to create a picture similar to that of a CT scan. CT is a more popular imaging test, but an MRI may be used to detect any spread of cancer into the bone.
Radionuclide Bone Scan
A slightly radioactive material is injected into the bloodstream. This material settles into damaged bone tissue, and a radioactivity-detecting camera then creates a picture of “hot spots” to which prostate cancer may have spread.
Lymph Node Biopsy
If a doctor suspects prostate cancer has begun to spread, he or she may perform this test, during which samples of lymph-node tissue are examined for signs of cancer.
This is a newer type of scan in which the patient is injected with a radioactive marker attached to an antibody protein that specifically binds to prostate tissue; this test can find prostate-cancer cells that have migrated to other parts of the body.