How Is Prostate Cancer Diagnosed? PSA, Digital Rectal Exam & Biopsy
Articles on Prostate Cancer
When should you be screened for prostate cancer?
A prostate cancer diagnosis may involve PSA tests, digital rectal exams, and biopsies.
Prostate cancer is one of the most common killers of men – it’s the second leading cause of cancer deaths among men in America. It’s largely a disease of men over 40, so it’s around this age doctors recommend the first prostate screening.
Age, ethnicity, family history, nationality, genetic factors, and obesity are all risk factors for prostate cancer, and any one of these is a reason to get checked. The good news is the prognosis for prostate cancer, depending on the stage at which it’s diagnosed, is good compared with some other cancers. Because the condition is so common, there’s a large set of data on what treatments are effective and lots of support for men with the disease
The prostate is a walnut-sized gland in men that wraps around the urethra below the bladder and produces the fluid portion of semen. Early signs of a cancerous prostate are blood in the urine and/or semen and pain or inability to urinate or ejaculate. Prostate cancer commonly metastasizes to lymph nodes in the pelvis and the bones.
The best treatment results come when prostate cancer is diagnosed early.
The first screening exam is a blood test to determine if there are abnormal Prostate-specific antigen (PSA) levels in your blood – PSA is a specific protein produced by the prostate. If the PSA is high, your doctor or specialist will perform a digital rectal exam, during which the doctor feels your prostate from inside your rectum with a gloved finger. Though it’s uncomfortable, a digital rectal exam may be far less uncomfortable and painful than the result of prostate cancer left undiagnosed.
If the results of the PSA test and rectal exam show abnormalities, your doctor may refer you to a urologist for a biopsy, and you will make treatment decisions with your doctor based on the biopsy results.
This article will discuss this diagnostic process in detail, as well as how prostate cancer is classified by type (i.e. the Gleason score).
What tests do health care professionals use to diagnose prostate cancer?
The diagnosis of prostate cancer ultimately is based on the pathologist’s review of tissue removed at the time of the prostate biopsy. An abnormal PSA and/or abnormal digital rectal examination often are present and are the indications for the prostate biopsy.
Digital rectal examination (DRE): As part of a physical examination, your doctor inserts a gloved and lubricated finger into your rectum and feels toward the front of your body. The prostate gland is a walnut or larger-sized gland immediately in front of the rectum, and beneath your bladder. The back portion of the prostate gland can be felt in this manner. Findings on this exam are compared to notes about the patient’s prior digital rectal examinations.
The exam is usually brief, and most find it uncomfortable due to the pressure used to adequately examine the prostate gland. Findings such as abnormal size, lumps, or nodules (hard areas within the prostate) may indicate prostate cancer.
The National Comprehensive Cancer Network (NCCN) notes that a DRE should not be used as a stand-alone test for the detection of prostate cancer but should be performed in men with an elevated PSA. The NCCN also notes that DRE may be considered as a baseline test in all patients, as it may help identify high-grade cancers associated with a normal PSA.
Prostate-specific antigen (PSA) blood test: The PSA blood test measures the level of a protein found in the blood that is produced by the prostate gland and helps keep semen in liquid form. The PSA test can indicate an increased likelihood of prostate cancer if the PSA is at an increased or elevated level or has changed significantly over time, but it does not provide a definitive diagnosis. Prostate cancer can be found in patients with a low PSA level, but this occurs less than 20% of the time.
If the PSA level is elevated (levels can depend upon your age, on the size of your prostate gland on examination, certain medications you may be taking, or recent sexual activity) or has increased significantly over time, further testing may be needed to rule out prostate cancer.
PSA measurements are often tracked over time to look for evidence of a change. The amount of time it takes for the PSA level to increase is referred to as PSA velocity. The time it takes for the PSA to double, known as the PSA doubling time, can be also tracked. PSA velocity and PSA doubling time can help your doctor determine whether prostate cancer may be present.
The presence of an abnormal result on digital rectal examination, or a new or progressive abnormality in a PSA test may lead to a referral to a physician who specializes in diseases of the urinary system (a urologist) who may perform further testing, such as a biopsy of the prostate gland.
Prostate biopsy: A biopsy refers to a procedure that involves taking a sample of tissue from an area in the body. Prostate cancer is only definitively diagnosed by finding cancer cells on a biopsy sample taken from the prostate gland.
- The urologist may have you stop medications such as blood thinners (for example, warfarin [Coumadin]),Clopidogrel, Xarelto, Eliquis, aspirin, ibuprofen [Advil, Motrin], and certain herbal supplements) before the biopsy.
- An antibiotic is often prescribed to help prevent an infection related to the procedure.
- Some urologists may place a small swab into your rectum a week or so before the procedure to determine the best antibiotic to give you (selective target antibiotic prophylaxis).
- You may be asked to do a cleansing enema at home before the biopsy appointment and will be instructed to take the antibiotic 30 to 60 minutes before the biopsy to prevent an infection.
- On the day of the biopsy, the doctor will apply a local anesthetic by injection or topically as a gel inside the rectum over the area of the prostate gland.
- You will be asked to lie on your side with your knees pulled up to your chest. Sometimes you may be asked to lie on your stomach.
- An ultrasound probe is then placed in the rectum. This device uses sound waves to take a picture of the prostate gland and helps guide the biopsy device.
- The device used is a spring-loaded needle that allows the urologist to remove tiny cores of tissue from the prostate gland.
- Usually, 12 cores are obtained, six from each side. Two cores are taken from the upper, middle, and lower portions of each side of the prostate gland.
- The cores are examined under the microscope by a pathologist (a doctor who specializes in examining tissues to make a diagnosis).
- Results may take several days.
If you do not have an anus (due to previous surgery), then a transperineal prostate biopsy is performed. During this procedure, which is often performed under sedation, the biopsy needle is inserted through the perineum (area between the scrotum and the anus) into the prostate.
A biopsy procedure is usually uncomplicated, with just some numbness, pain, or tenderness in the area for a short time afterward. Occasionally, a patient has some blood in the urine, stool, or ejaculate after the procedure. Rarely, the patient may develop an infection after a biopsy procedure (urinary tract infection, prostate infection, testis infection) or be unable to urinate. If one develops a fever after the procedure, has continued blood in the urine or ejaculate, or has troubles urinating, further evaluation by the performing doctor is needed.
Prostate cancer biopsy results
The result of the pathologist’s analysis of the biopsy cores under the microscope is the only way to diagnose prostate cancer. The prostate biopsy technique samples many areas of the prostate but rarely the biopsy can miss small areas of prostate cancer in the prostate. Thus, if the initial biopsy results are negative but the urologist is still suspicious based on the results of the examination, the ultrasound images seen during the procedure, or the PSA, additional biopsies or tests may be recommended.
The pathologist’s report on the biopsy sample showing prostate cancer will contain much detailed information. The size of the biopsy core and the percentage of involvement of each core will be reported. Most importantly the prostate cancer present will be assigned a numerical score, which is usually expressed as a sum of two numbers (for example, 3 + 4) and is referred to as the Gleason Score. This characterizes the appearance of the cancer cells and helps predict its likely level of aggressiveness in the body.
- A Gleason score of 6 or less indicates low-grade prostate cancer,
- whereas scores of 8-10 indicate high-grade prostate cancer.
A new prostate cancer grading system was developed in 2014 to help assess risk and assign a Gleason grade group. This grade group is particularly useful in Gleason score 7, where the predominant cell type could be a 4 or a 3, which may impact prostate cancer risk.
- Gleason grade group 1: Gleason score < 6
- Gleason grade group 2: Gleason score 3+4= 7
- Gleason grade group 3: Gleason score 4+3 = 7
- Gleason grade group 4: Gleason 4+4 =8, 3+5 = 8 and 5+3 = 8
- Gleason grade group 5: Gleason score 9 and 10
The Gleason score and the extent of involvement of the biopsy core expressed as a percentage, as well as the PSA level as well as your general state of health and otherwise estimated life expectancy, all help to allow doctors to make their best recommendations for you regarding how your cancer should be treated.
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How accurate is the PSA test?
The PSA test is a tool for use by your doctor, but it is not a perfect way to tell whether or not a patient has prostate cancer because is not sensitive enough to pick up all prostate cancers.
- It is not specific enough in that it may be elevated in people without prostate cancer, such as those whose prostate glands are infected, inflamed, or enlarged but not cancerous.
- The PSA level can be affected by medications used to treat benign enlargement of the prostate (BPH), 5 alpha reductase inhibitors (finasteride, dutasteride), which lower the PSA by approximately 50% within 6 months to a year of being on this medication.
- It is also elevated for several days after a digital rectal exam or after ejaculation.
Nevertheless, it accurately measures the amount of PSA in the blood at the time that it is drawn. Once a single PSA test has been obtained, the level of the PSA on follow-up tests is not as important as the rate of change of the PSA (how quickly it is increasing).
The interpretation of the PSA result must be done with care. PSA results must be, for example, interpreted in the context of the patient’s age.
- Younger men (under 70 years of age and definitely under 60 years of age) may have either more aggressive prostate cancers or live long enough to experience the adverse effects of undetected/untreated prostate cancer.
- Conversely, men over 70 often have more indolent or slow-growing prostate cancers or other medical conditions that may be greater threats to their lives over the next 10 years than may prostate cancer, and thus less aggressive evaluation and treatment may be warranted.
Prostate cancer risk increases as men age.
- It is estimated 16% of men will be diagnosed with prostate cancer in their lifetime, and yet only 3% will die of it.
- Many men likely have small prostate cancers present by the time they are over 60 years of age, with estimates ranging from 30%-40% having prostate cancer cells in their prostates.
- The risk of developing these small cancers also likely further increases with age. Most of these cancers are not life-threatening. They are very slow-growing and not aggressive in their tendency to spread as they are never discovered or symptomatic during the men’s lives.
- Diagnosing these prostate cancers may only increase the cost and result in treatment-related complications in these men.
Talk to your doctor about the risks and benefits of prostate cancer screening and having PSA testing if you are 40 years of age with a family history of prostate cancer (or age 50 if you do not have a family history), or are of African-American ancestry. The test results should be considered in the context of the prostate size, family history of prostate cancer, race and ethnicity, and rectal examination findings. Further there should be attention given to the pattern of change in his serial PSA measurements.
Numerous different ways to refine the use of PSA testing have been attempted. Some of these include evaluations of the
- PSA doubling time, which refers to how long it has taken for the PSA to double;
- PSA velocity, which looks at how rapidly the PSA values have changed over time;
- PSA density, which looks at the PSA result and considers the prostate gland volume as determined on ultrasound evaluation; and
- PSA fractionation, which is another test that measures the amount of free PSA versus protein-bound PSA in the bloodstream.
The lower the percentage of free PSA, the higher the risk of cancer.
In prostate cancer patients whose PSA was initially elevated, the PSA is an excellent tool to assist in decisions about care and in follow-up both during and after treatment.
Other tests that may help evaluate risk for prostate cancer and need for biopsy are used to decide treatment.
Several prostate cancer risk calculators have been developed to help determine the risk of having prostate cancer using multiple factors.
- Some of these risk calculators include Sunnybrook-, ERSPC-, and PCPT-based risk calculators.
- The calculators determine the risk of having prostate cancer on biopsy by combining several factors including age, family history of prostate cancer, race, DRE, and PSA.
- These calculators may help determine the need for biopsy but should be used in conjunction with your doctor’s clinical judgment and patient preferences.
The use of MRI (magnetic resonance imaging), multiparametric MRI, to select individuals who need a prostate biopsy or to guide needle placement during the biopsy, is controversial. Currently, the NCCN does not recommend that MRI alone should be used to decide whether a biopsy should be performed and notes that a negative MRI does not indicate that a biopsy should be deferred in a man with indications for a first-time biopsy. The NCCN also doesn’t uniformly support the use of this study to direct prostate biopsy needle placement at this time.
Biomarkers have been developed to help define the probability of prostate cancer prior to proceeding to biopsy. The goals of the biomarker tests are to decrease the risk of unnecessary biopsies and increase the likelihood of cancer detection without missing a significant number of prostate cancers.
- The biomarker tests may be most useful in men with PSA levels between 3 and 10 ng/mL.
- Currently, the NCCN recommends consideration of percent free PSA (%fPSA), Prostate Health Index (PHI), and 4Kscore in patients with PSA levels > 3 ng/mL who have not had an initial prostate biopsy.
- For individuals who have had at least one negative prostate biopsy but who are thought to be at higher risk for prostate cancer (increasing PSA), the NCCN recommends %fPSA, PHI, 4Kscore, PCA3, and ConfirmMDx.
- Select MDx is a biomarker that can be obtained prior to initial biopsy and after negative biopsy.
At present, no test has been established to be superior to another. Prior to having such studies done, it is advisable to ensure that your insurance company covers these tests.
What specialists identify and treat prostate cancer?
There are several different types of specialists involved in the identification and treatment of prostate cancer.
- The primary care provider (PCP) may be the initial medical doctor to discuss prostate cancer screening and/or become concerned about the risk of prostate cancer (because of abnormal rectal examination and/or elevated PSA or family history of prostate cancer [brother or father or multiple family members diagnosed with prostate cancer at < 60 years of age]) during your routine evaluations or due to symptoms and refer you to a urologist for further evaluation.
- Urologists are the specialists who will initially be involved in the diagnosis of prostate cancer and will perform the prostate biopsy. Depending on the grade and stage of the prostate cancer at the time of the diagnosis, additional specialists may be involved in your care. Urologists perform surgical-based treatments for prostate cancer (radical prostatectomy), minimally invasive treatments (cryotherapy, brachytherapy), and prescribe medications (hormonal therapy).
- Medical oncologists are doctors who specialize in the treatment of cancer. Medical oncologists treat prostate cancer with a variety of medical therapies, including chemotherapy, immune/vaccine, and hormonal therapy.
- Radiation oncologists are specialists who treat cancer with ionizing radiation. This radiation may be given externally (external beam radiation therapy) or internally through the placement of small radioactive pellets into the prostate (brachytherapy).
Often urologists, medical oncologists, and radiation oncologists work together in a multidisciplinary team to review your case and you may meet with one, two, or all of these physicians at some point during your prostate cancer treatment.
Medically Reviewed on 11/16/2021
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