How is prostate cancer found?
Screening refers to testing to find a disease such as cancer in people who do not have symptoms of that disease. Prostate cancer can often be found early by testing the amount of PSA (prostate-specific antigen) in a man’s blood. Another way prostate cancer is found early is when the doctor does a digital rectal exam (DRE). If prostate cancer is found as a result of either one of these tests, it has probably been found at an early, more treatable stage.
Since about 1990 it has become fairly common for men in the United States to have tests to find prostate cancer early. The prostate cancer death rate has dropped, too. But we do not yet know if this drop is the direct result of the tests or if it might be caused by something else, like better treatments.
There is no question that screening can help find many prostate cancers early, but these tests are not perfect. These tests can sometimes have abnormal results even when a man does not have cancer, or they can have normal results even when a man does have cancer. Uncertain or false test results could cause confusion and worry.
Even if these tests find cancer, they can't tell how dangerous the cancer is. The problem is that some prostate cancers are slow-growing and may never cause problems. But because of a high PSA level, many men will be found to have prostate cancer that may never have led to their deaths or even caused any problems. Often these men are treated with either surgery or radiation, either because their doctor can't be sure how fast the cancer might spread or because the man is uncomfortable knowing he has cancer and not having treatment. These treatments can lead to urinary or bowel problems or problems with sex. Doctors and patients are still trying to decide who should get treatment and who can be followed without treatment (called watchful waiting).
Studies are being done to try to figure out if early tests for prostate cancer in large groups of men will lower the prostate cancer death rate and help men live longer. The most recent results from 2 large studies didn't offer clear answers.
Until more is known, you should talk to your doctor about whether or not you should be tested. Things to take into account are your age, your health, and the benefits and side effects of screening and treatment. If you are young and you get prostate cancer, it will probably shorten your life if it is not caught early. But if you are older or in poor health, then prostate cancer may never become a major problem because it often grows so slowly.
What the American Cancer Society recommends
The American Cancer Society recommends that men have a chance to make an informed decision with their health care provider about whether to be screened for prostate cancer. They should first get information about what is known and what is not known about the risks and possible benefits of prostate cancer screening. Men should not be screened unless they have received this information.
The talk about screening should take place at age 50 for men who are at average risk of prostate cancer.
This talk should take place starting at age 45 for men at high risk of getting prostate cancer. This includes African-American men and men who have a father, brother, or son found to have prostate cancer at an early age (younger than age 65).
This talk should take place at age 40 for men at even higher risk (those with more than one close family member [father, brothers, sons] who had prostate cancer at an early age).
After this discussion, men who want to be screened should be tested with the PSA blood test. The digital rectal exam (DRE) may also be done as a part of screening.
If, after this talk, a man is not able to decide whether testing is right for him, the screening decision can be made by the health care provider, who should take into account the patient’s overall health and values.
If no prostate cancer is found as a result of screening, the time between future screenings depends on the results of the PSA blood test:
- Men who have a PSA of less than 2.5 ng/ml (see below) may only need to be retested every 2 years.
- Screening should be done yearly for men whose PSA level is 2.5 ng/ml or higher.
Because prostate cancer often grows slowly, men without symptoms of prostate cancer who aren't likely to live 10 more years should not be offered testing since they are not likely to benefit.
Even after a decision about testing has been made, men and their doctors should keep on talking about the pros and cons of testing as new information about the benefits and risks of testing becomes known. The patient's health, values, and choices can change as well.
PSA blood test
PSA (prostate-specific antigen) is a substance made by the prostate gland. Although PSA is mostly found in semen, a small amount is also found in the blood. Most healthy men have levels under 4 ng/mL (nanograms per milliliter) of blood. The chance of having prostate cancer goes up as the PSA level goes up. If your level is between 4 and 10, you have about a 1 in 4 chance of having prostate cancer. If it is above 10, your chance is over 50%. But some men with a PSA below 4 can also have prostate cancer.
Factors other than cancer can also cause the PSA level to go up, such as:
- An enlarged prostate like BPH (benign prostatic hyperplasia– not cancer), which many men get as they grow older
- Older age
- Infection or inflammation of the prostate gland (prostatitis)
- Ejaculation (may raise PSA for a short time)
- Riding a bicycle (but not all studies have found this)
- Certain urology tests
- Certain medicines, such as testosterone
Some things can cause PSA levels to go down, even when cancer is present:
- Certain medicines: Some drugs used to treat BPH or urinary symptoms may lower PSA levels. You should tell your doctor if you are taking medicines for these problems, because the doctor will need to adjust the reading.
- Herbal mixtures: Some mixtures that are sold as dietary supplements may also hide a high PSA level. This is why it is important to let your doctor know if you are taking any type of supplement– even ones not meant for prostate health. Saw palmetto (an herb used by some men to treat BPH) does not seem to affect the measurement of PSA.
- Obesity: Very overweight men tend to have lower PSA levels.
- Aspirin: Men taking aspirin regularly may have lower PSA levels. This effect may be greater in non-smokers. More research is needed to confirm this. If you take aspirin regularly (such as to help prevent heart disease), talk to your doctor before you stop taking it for any reason.
Newer types of PSA tests
There are a number of new types of PSA tests that might help to show whether or not you need more testing. Not all doctors agree on how to use these new PSA tests. You should talk to your doctor about your cancer risk and any tests that you are having.
Other uses of the PSA blood test
The PSA test is used mainly to detect prostate cancer early, but it is also useful if prostate cancer has already been found (see below).
DRE (digital rectal exam)
To do the DRE, the doctor puts a gloved, lubricated finger into the rectum to feel for any bumps or hard areas on the prostate that might be cancer. The prostate gland is next to the rectum, and most cancers begin in the part of the gland that can be felt by rectal exam. The exam can be uncomfortable (especially in men with hemorrhoids), but it usually isn't painful and takes only a short time.
The DRE is less effective than the PSA blood test in finding prostate cancer, but it can sometimes find cancers in men with normal PSA levels. For this reason, it may be done as a part of prostate cancer screening. The DRE is also used once a man is known to have prostate cancer. It can help tell whether the cancer has spread beyond his prostate gland. It can also be used to find cancer that has come back after treatment.
Signs and symptoms of prostate cancer
Early prostate cancer often causes no symptoms. It may be found by a PSA test or DRE. Problems with urinating could be a sign of advanced prostate cancer, but more often this problem is caused by a less serious disease known as BPH (benign prostatic hyperplasia).
Other possible symptoms of advanced prostate cancer are:
- Trouble having or keeping an erection (impotence)
- Blood in the urine
- Pain in the spine, hips, ribs, or other bones
- Weakness or numbness in the legs or feet
- Loss of bladder or bowel control
Once again, other diseases also can cause these symptoms.
Medical history and physical exam
If your doctor suspects you might have prostate cancer, he or she will ask you about any symptoms you are having, such as any urinary or sexual problems, and how long you have had them. Your doctor may also ask about bone pain, which could be a sign that the cancer might have spread to your bones.
Your doctor will also do a physical exam and will check other parts of your body to see if the cancer has spread.
PSA blood test
The prostate-specific antigen (PSA) blood test is used mainly to try to find prostate cancer early in men without symptoms (see above). But it is also one of the first tests done in men who have symptoms that might be caused by prostate cancer.
The PSA test can also be useful if prostate cancer has already been found.
- It can be used along with physical exam results and tumor grade (from the biopsy, described further on) to help decide if other tests (such as CT scans or bone scans) are needed.
- It can help tell if your cancer is still confined to the prostate gland. This may affect your treatment options.
- The PSA test can also be used to help show if treatment is working, how well it is working, or whether the cancer has come back after treatment.
- If you choose a "watchful waiting" approach, the PSA level can be used to help decide if the cancer is growing and whether you should think about starting treatment.
- If you are having hormone therapy or chemo, the PSA level can help tell how well the treatment is working or when it may be time to try a different form of treatment.
If certain symptoms or the results of tests like the PSA blood test and/or DRE suggest that you might have prostate cancer, your doctor will do a prostate biopsy to find out.
During a biopsy, tissue from the prostate is removed so it can be sent to the lab to see if it contains cancer cells. A core needle biopsy is the type of biopsy used most often. Here is how it's done:
A small probe is placed in the rectum. The probe gives off sound waves which make a picture of the prostate on a video screen. This technique is called TRUS (transrectal ultrasound). Guided by TRUS, the doctor puts a thin, hollow needle through the wall of the rectum into the prostate gland. When the needle is pulled out, it takes out a small piece of prostate tissue (called a core). This is done from 8 to18 times, but most doctors will take about 12 samples. Samples are often taken from different parts of the prostate. Ask your doctor how many samples will be taken.
Although the test sounds painful, it usually causes little discomfort because it is done very quickly. The doctor can numb the area ahead of time. You might want to ask your doctor about doing this.
The biopsy takes about 10 minutes and is usually done in the doctor's office. You will likely be given antibiotics to take ahead of time and afterwards to reduce the chance of infection. For a few days afterwards you may notice some soreness, blood in your urine, or light bleeding from the rectum. Many men also see some blood in their semen or have rust colored semen, which can last for several weeks after the biopsy.
Cancer may only be present in a small area of the prostate. Because of this, sometimes the biopsy will miss the cancer even when it is there. This is known as a "false negative" result. If your biopsy doesn't show cancer, but your doctor still strongly suspects cancer, a repeat biopsy may be needed.
Grading the prostate cancer
The biopsy sample will be sent to a lab. A doctor there will look for cancer cells in the sample. If cancer is present, the sample will be graded. Grading the cancer helps to predict how fast the cancer is likely to grow and spread.
Prostate cancers are graded on the basis of how closely the cells in the sample look like normal prostate cells. Those that look very different from normal cells are likely to mean a cancer that grows faster. The system used most often for grading prostate cancer is called the Gleason system.
Samples from 2 areas of the prostate are each graded from 1 to 5, and the number grades are added to give a Gleason score or sum of between 2 and 10. The lower the number, the more the cells in the sample look like normal prostate cells. A higher score means the cells look less normal and the cancer is likely to grow more quickly. Ask your doctor to explain the grade of your cancer because it is an important factor in making treatment decisions.
Other things you may see on a biopsy report
The biopsy report tells you the grade of the cancer (if it is present), but it also often provides other information that may give a better idea of the scope of the cancer. These can include:
- The number of biopsy core samples that contain cancer (for example, "7 out of 12")
- The amount of cancer in each of the cores (given as a percentage)
- Whether the cancer is on one side (left or right) of the prostate or both sides (bilateral)
- Sometimes when the prostate cells are seen under the microscope, they don't look like cancer, but they're not quite normal, either. These results are often reported as suspicious. Your doctor can explain what these results might mean in your case.
Not all men with prostate cancer need to have more tests, but for those who do, the tests below are sometimes used. Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. The imaging tests used most often for prostate cancer include:
Transrectal ultrasound (TRUS)
Transrectal ultrasound (TRUS) uses sound waves to make a picture of the prostate on a video screen. For this test, a small probe is placed in the rectum. It gives off sound waves, which enter the prostate and create echoes that are picked up by the probe. A computer turns the pattern of echoes into a black and white picture of the prostate.
The test often takes less than 10 minutes. The TRUS probe is about the width of a finger and is lubricated before it is placed in your rectum. You will feel some pressure when it is put in, but it is usually not painful.
TRUS is usually not used as a screening test for prostate cancer because it doesn't often show early cancer. It is most often used during a prostate biopsy to guide the biopsy needles into the right area of the prostate.
TRUS is used for other things as well. It can be used to measure the size of the prostate gland, which can help the doctor interpret the PSA level. It may also affect which treatment options a man has. It is also used as a guide during some forms of treatment such as cryosurgery (discussed in the Treatment section).
If prostate cancer spreads to distant places, it often goes to the bones first. (Even when this happens, it is still prostate cancer, not bone cancer.) A bone scan is done to show whether the cancer has spread from the prostate gland to bones.
For this test, a radioactive material is put into your vein (given IV). The dose of radiation is very low. The radioactive substance is drawn to damaged areas of bone throughout the body and shows up on the bone scan as "hot spots." These places could be cancer, or they could be caused by arthritis or other bone diseases. To find out, more tests may need to be done.
CT scan (computed tomography)
A CT (also known as a CAT scan) is a special type of x-ray. A series of pictures is taken from many angles. A computer combines the pictures to give a detailed image. For some scans, you may be asked to drink 1 or 2 pints of a liquid that outlines the intestine so that it looks different from any tumors. You might also have a harmless dye put into your vein (given IV). A few people are allergic and get hives. Rarely, more serious problems, like trouble breathing or low blood pressure, can occur. Be sure to tell your doctor if you have any allergies or have ever had trouble with any contrast material used for x-rays.
A CT scan can help tell if your prostate cancer has spread into lymph nodes in your pelvis. (Lymph nodes are a network of bean-sized collections of white blood cells that fight infection.) CT scans take longer than regular x-rays. You need to lie still on a table inside a ring-shaped machine. You might feel a bit confined by the ring you have to lie in while the pictures are being taken.
This test can sometimes tell whether prostate cancer has spread into nearby lymph nodes. If your prostate cancer has come back after treatment, the CT scan can often tell whether it is growing into other organs in your pelvis. CT scans are not as useful as MRIs for looking at the prostate gland itself.
MRI (magnetic resonance imaging)
This test is like a CT scan except that it uses radio waves and strong magnets instead of x-rays to make the pictures. The MRI gives a very clear picture to help the doctor see whether the cancer has spread to the seminal vesicles or other nearby structures. Because the scanners use magnets, people with pacemakers, certain heart valves, or other medical implants may not be able to get an MRI.
MRI scans take longer than CT scans – often up to an hour. During the scan you lie in a narrow tube which is confining and can upset some people. In order to get a better picture, many doctors will place a probe inside the rectum. It must stay in place for 30 to 45 minutes and can be uncomfortable. Like CT scans, a contrast dye might be put into your vein, but this is done less often.
Like the bone scan, the ProstaScint scan uses low levels of a radioactive substance to find cancer that has spread beyond the prostate. The substance is put into your vein and is drawn to prostate cells anywhere in the body. You will be asked to lie on a table while a special camera takes pictures of your body. This is usually done about half an hour after the injection and again 3 to 5 days later.
This test can find the spread of prostate cancer to lymph nodes and other organs, although it is not as helpful for looking at the area around the prostate itself. Doctors are not yet sure how useful this test is and most don't use it for men who have just been diagnosed with prostate cancer.
Lymph node biopsy
In a lymph node biopsy, one or more lymph nodes are removed to see if they contain cancer cells. If your cancer has spread to nearby lymph nodes, surgery to cure the cancer is usually not an option and the doctor will look at other treatment choices. Lymph node biopsies are rarely done unless your doctor is concerned that the cancer has spread. There are different types of biopsies.
The surgeon might remove lymph nodes through a cut (incision) in the lower part of the belly (abdomen). This biopsy is often done during the operation to remove the prostate. In some cases, the lymph nodes are looked at in the lab while you are still asleep (under anesthesia). The results will help the surgeon decide whether or not to go on with the surgery. If the nodes contain cancer, the operation might be stopped. This is because taking out the prostate would be unlikely to cure the cancer, but it could still cause serious problems or side effects. But more often, the prostate is removed even if the lymph nodes contain cancer.
A laparoscope is a long, thin tube with a small camera on the end. It is put into the belly (abdomen) through a small cut (incision) in the skin to let the surgeon see inside without making a large cut. Other small cuts are made to put in long instruments to remove lymph nodes. Recovery usually takes only 1 or 2 days and there is very little scarring from this operation. This method is not common, but it is sometimes used when a man is not having surgery, for instance for men who choose treatment with radiation.
Fine needle aspiration (FNA)
If a CT or MRI scan shows that lymph nodes near the prostate seem to be swollen, a sample of cells may be taken by doing a fine needle aspiration (FNA). The doctor first numbs the skin and then uses the CT scan to guide a long, thin (fine) needle through the skin and into the lymph nodes. This is an outpatient procedure and you can go home a few hours later.
Last Medical Review: 03/09/2012
Last Revised: 01/17/2013