Prostate Cancer: Screening, Diagnosis and Prognosis
Screening Tests, Diagnostic Biopsies, Imaging Techniques and Whole-Body Scans
Prostate Cancer Diagnosis
Doctors use many tests to find or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.
For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory.
Not all tests listed below are commonly used for every person. Your doctor may consider these factors when choosing a diagnostic test:
- The type of cancer suspected
- Your signs and symptoms
- Your age and general health
- The results of earlier medical tests
Prostate Cancer Screening
“Screening” means testing for a disease even if you have no symptoms. The prostate specific antigen (PSA) blood test, digital rectal examination (DRE) and biomarker tests are some of the tests that are used to screen for prostate cancer. Both are used to detect cancer early. However, these tests are not perfect. Abnormal results with either test may be due to benign prostatic enlargement (BPH) or infection, rather than cancer.
Testing healthy men with no symptoms for prostate cancer is controversial. There is some disagreement among medical organizations whether the benefits of testing outweigh the potential risks.
If prostate cancer is suspected, a physical examination and the following tests may be used to decide if more diagnostic tests are needed:
1. Prostate Specific Antigen (PSA) Test:
Prostate-specific antigen (PSA) is a type of protein released by prostate tissue that is found in higher levels in the blood. Levels can be raised when there is abnormal activity in the prostate, including prostate cancer, benign prostatic hypertrophy (BPH), or inflammation of the prostate.
Doctors can look at features of the prostate-specific antigen (PSA) value to decide if a biopsy is needed, such as absolute level, change over time (also known as “PSA velocity”), and level about prostate size.
2. Free Prostate Specific Antigen (PSA) Test:
There is a version of the prostate-specific antigen (PSA) test that allows the doctor to measure a specific component, called the “free” PSA. Free PSA is found in the bloodstream and is not bound to proteins.
A standard prostate-specific antigen (PSA) measures total PSA, which includes both PSA that is and is not bound to proteins. The free prostate-specific antigen (PSA) test measures the ratio of free PSA to total PSA. Knowing this ratio or percent can sometimes help find out if an elevated PSA level is more likely to be caused by a malignant condition like prostate cancer.
3. Digital Rectal Examination (DRE):
A doctor uses a digital rectal examination (DRE) to find abnormal parts of the prostate by feeling the area using a finger. It is not very precise and not every doctor has expertise in the technique; therefore, digital rectal examination (DRE) does not usually detect early prostate cancer.
4. Biomarker Tests:
A biomarker is a substance that is found in the blood, urine, or body tissues of a person with cancer. It is made by the tumor or by the body in response to cancer.
A biomarker may also be called a tumor marker. Biomarker tests for prostate cancer include the 4K score, which predicts the chances someone will develop high-risk prostate cancer, and the Prostate Health Index (PHI), which predicts the chances someone will develop prostate cancer.
For people diagnosed with prostate cancer by biopsy, there are times when a genomic test, such as Oncotype Dx Prostate, Prolaris, Decipher, and ProMark, can provide additional information to inform a decision about how prostate cancer is managed.
This includes when those with certain low-risk or intermediate-risk localized prostate cancer are considering active surveillance. It also may include using the Decipher test to help decide whether more treatment should be considered in certain patients following surgical removal of the prostate, called prostatectomy.
If a biomarker test is used, the results should always be evaluated in combination with all other available information.
Talk with your doctor for more information about biomarker tests, what they mean, and how the results might or might not affect your treatment plan.
If the PSA or DRE test results are abnormal, then further tests will be used to confirm whether a person has prostate cancer. Many tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis.
A biopsy is the removal of a small amount of tissue for examination under a microscope. To get a tissue sample, a surgeon most often uses transrectal ultrasound (TRUS) and a biopsy tool to take very small slivers of prostate tissue.
Biopsy specimens will be taken from several areas of the prostate. This is done to make sure that a good sample is taken for examination. Most people will have 12 to 14 pieces of tissue removed, and the procedure can take 20 to 30 minutes to complete.
This procedure is usually done at the hospital or doctor’s office without needing to stay overnight. The patient is given local anesthesia beforehand to numb the area and usually receives antibiotics before the procedure to prevent infection.
The ultrasound tool is inserted into the rectum and then the biopsy needle is passed through the rectum and into the prostate gland to collect tissue samples.
There is a risk of infection associated with transrectal prostate biopsy, which is why some doctors choose to use transperineal prostate biopsy instead. This biopsy is also guided by transrectal ultrasound (TRUS), but the biopsy needle goes through the skin of the perineum and into the prostate gland.
The perineum is the space between the scrotum and the anus. By passing the needle through the skin instead of the rectum, this procedure lowers the risk of infection.
A pathologist then analyzes the sample(s) under a microscope. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.
Ask to review the results of the pathology report with your health care team.
2. MRI Fusion Biopsy:
An MRI fusion biopsy combines an MRI scan with TRUS. Evaluation with a prostate MRI scan has become a routine procedure in clinical practice. The patient first receives an MRI scan to identify suspicious areas of the prostate that require further evaluation.
The patient then has an ultrasound of the prostate. Computer software combines these images to produce a 3D image that helps target a precise area for the biopsy.
Although it may not eliminate the need for repeat biopsies, an MRI fusion biopsy can better identify areas that are more likely to be cancerous than other methods. An MRI fusion biopsy should only be performed by someone with expertise in the procedure.
3. Transrectal Ultrasound (TRUS):
A doctor inserts a probe into the rectum that takes a picture of the prostate using sound waves that bounce off the prostate. A TRUS is usually done at the same time as a biopsy.
Imaging Techniques and Whole-Body Scans
To find out if cancer has spread outside of the prostate, doctors may perform the imaging tests listed below. Doctors can estimate the risk of spread, called metastasis, based on PSA levels, tumor grade, and other factors, but an imaging test can confirm and provide information about the cancer’s location.
Imaging tests may not always be needed. A CT scan or bone scan may not be necessary for those with no symptoms and low-risk, early-stage prostate cancer, as determined with information from the PSA test and biopsy.
For people with advanced prostate cancer, ASCO recommends that 1 or more of the imaging tests below be done to provide more information about the disease and help plan the best treatment.
This includes when there is a newly diagnosed, high-risk cancer; if metastasis is suspected or confirmed; if cancer has returned following treatment; or when cancer grows during the treatment period
1. Whole-Body Bone Scan:
A bone scan uses a radioactive tracer (Technetium-99) to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone where metabolic activity has occurred. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image.
It is important to know that structural changes to the bone, such as arthritis or bone injuries like fractures, can also be interpreted as abnormal and need to be evaluated by a doctor to make sure they are not cancer.
2. Computed Tomography (CT or CAT) Scan:
A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors.
A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.
3. Magnetic Resonance Imaging (MRI):
An MRI scan uses magnetic fields, not x-rays, to produce detailed images of the body. An MRI can be used to measure the tumor’s size, and a scan can focus specifically on the area of the prostate or the whole body. A special dye called a contrast medium is given before the scan to create a clearer picture, which is injected into a patient’s vein.
4. Positron Emission Tomography (PET) or PET-CT Scan:
A PET scan is usually combined with a CT scan, called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body.
A small amount of a radioactive substance is injected into the patient’s body. This substance is taken up by cells that use the most energy or are more biologically active. Because cancer tends to use energy and is biologically active, it absorbs more of the radioactive substance.
A scanner then detects this substance to produce images of the inside of the body. For many types of cancer, a PET-CT scan uses fluorodeoxyglucose (FDG) as the substance that is imaged; however, FDG is not a useful substance for initial imaging in prostate cancer and should not be routinely used.
In people with a high risk of metastasis or who are suspected to have a biochemical or PSA, a PET scan using gallium-68 PSMA-11 may be recommended.
In this type of scan, the gallium-68 binds to prostate specific membrane antigen (PSMA), which is often in higher levels in prostate cancer cells and shows places where the cancer has spread.
Researchers are investigating using different substances with PET scans to find prostate cancer. For example, sodium fluoride is absorbed by bones, and its use in a PET scan may improve the chances of finding prostate cancer that has spread to the bone. Other substances being studied include choline acetate and fluciclovine.
After diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging.
Prostate Cancer Prevalence and Survival Rates
Prostate cancer is the most common cancer among men, except for skin cancer. This year, an estimated 248,530 men in the United States will be diagnosed with prostate cancer.
Around 60% of cases are diagnosed in men age 65 or older. The average age of diagnosis is 66 years. The disease rarely occurs in those younger than 40. The number of new cases diagnosed in Black men is nearly 80% higher than the number of new cases diagnosed in white men.
The 5-year survival rate tells you what percent of people live at least 5 years after the cancer is found. Percent means how many out of 100. The 5-year survival rate for people with prostate cancer is 98%. The 10-year survival rate is also 98%.
Most prostate cancers (89%) are found when the disease is in only the prostate and nearby organs. This is referred to as the local or regional stage.
The 5-year survival rate for most people with local or regional prostate cancer is nearly 100%. For people diagnosed with prostate cancer that has spread to other parts of the body, the 5-year survival rate is 30%.
Prostate cancer is the second leading cause of cancer death in men in the United States. It is estimated that 34,130 deaths from this disease will occur this year.
A person’s individual survival depends on the type of prostate cancer and the stage of the disease. There are more than 3.1 million survivors of prostate cancer in the United States today.
It is important to remember that statistics on the survival rates for people with prostate cancer are an estimate. The estimate comes from annual data based on the number of people with this cancer in the United States.
Also, experts measure the survival statistics every 5 years. So the estimate may not show the results of better diagnosis or treatment available for less than 5 years.