Prostate cancer is the most common cancer after skin cancer in men in the United States.
In some men, it is slow growing and unlikely to cause serious problems. In others, the disease is very aggressive. If it’s detected early, prostate cancer is highly treatable, and most men survive.
- What is prostate cancer?
- Understanding your prostate
- Testing for metastasis
- Causes and risk factors
- How common is prostate cancer?
- Next steps
What is prostate cancer?
Prostate cancer starts in the prostate, a gland located below the bladder and in front of the rectum.
- The prostate contains several types of cells, but nearly all prostate cancers develop from glandular cells, which make fluid that becomes part of semen.
- Prostate cancer cells can spread by invading nearby organs and tissues, such as the bladder or rectum, or by traveling through the blood or lymph to other parts of the body. This is known as metastatic prostate cancer.
- Other than the lymph nodes near the prostate, the most common site of prostate cancer spread, or metastasis, is the bones, especially in the spine.
- In some cases, prostate cancer has already metastasized by the time a man learns he has the disease.
Many doctors used to consider prostate cancer in older men to be just part of the normal aging process, and the disease was largely ignored, except when it struck younger men. Now there are newer, better treatments for prostate cancer, and many men who have or had prostate cancer at any age are leading active, productive lives.
Understanding your prostate
Your prostate makes and stores seminal fluid — a milky liquid that protects and nourishes sperm. Your prostate surrounds part of your urethra, the tube that carries urine and semen out of your body.
Many men develop a noncancerous condition called benign prostatic hyperplasia (BPH), or enlargement of the prostate. If the prostate, which is normally about the size of a walnut, grows too large, it can slow or block the flow of urine.
- BPH typically develops in the zone of the prostate that surrounds the urethra (transition zone). For this reason BPH may cause difficulty with urination.
- BPH does not lead to or increase the chance of prostate cancer.
Most prostate cancer develops in the zone of the prostate near the rectum (peripheral zone), which is why a digital rectal exam is a useful screening test.
- This is why prostate cancer typically does not interfere with urination as much as BPH does.
- Even so, because the prostate is close to the urethra and several other important structures, prostate cancer and its treatment can disrupt normal urinary, bowel and sexual function.
Symptoms of prostate cancer
Prostate cancer symptoms typically don’t appear early in the disease. In many men, doctors first detect signs of prostate cancer during a routine check-up.
More advanced prostate cancer symptoms may include:
- Weak or interrupted flow of urine
- Urinating often (especially at night)
- Difficulty starting or stopping urination
- Pain or burning during urination
- Difficulty getting or sustaining an erection (impotence)
- Painful ejaculation
- Blood in the urine or semen
- Frequent pain or stiffness in the lower back, hips or upper thighs
Many of these symptoms are also seen with noncancerous diseases. They may be similar to BPH symptoms or prostatitis symptoms. (Prostatitis is infection of the prostate.) If you are experiencing any signs and symptoms of prostate cancer, call your doctor.
Diagnosing prostate cancer
When it is diagnosed early, prostate cancer is curable. Good prostate cancer screening tests, like the prostate-specific antigen (PSA) test, have resulted in early diagnosis in about 80 percent of men with the disease. According to the American Cancer Society, all of these men survive at least five years.
Whether cancer is suspected based on symptoms or a digital rectal exam or PSA test, the actual diagnosis is made with a prostate biopsy, a procedure in which samples of your prostate are removed and examined under a microscope.
A core needle biopsy, the main method for diagnosing prostate cancer, is typically performed in a doctor’s office by a urologist.
- Using transrectal ultrasound (TRUS) and a local anesthetic, the doctor inserts a needle into your prostate through a probe in your rectum.
- The doctor uses the needle to take about 12 samples of cells.
- The procedure typically takes no more than 5 to 10 minutes, and you should have very little discomfort.
Your biopsy samples will be sent to a lab to be examined by a pathologist. Getting results usually takes a few days.
- If your biopsy reveals that you are cancer-free, you may still need to continue with routine screenings. Talk with your doctor about this.
- If cancer cells are present, certain information available from the biopsy, such as the grade and stage of your cancer, helps your doctor determine the best treatment options for you and the outlook for your recovery.
An imaging test called an Axumin positron emission tomography (PET) scan may help detect prostate cancer that has come back in men whose PSA levels rise after they've had treatment. Before the scan, you receive an injection of fluciclovine F 18 (Axumin), a radioactive agent that tends to collect in areas of cancer activity, which then light up on your scan.
Grading prostate cancer: the Gleason system
The Gleason system is used to define the grade of your prostate cancer. Grade is an indication of how quickly the tumor is likely to grow and spread — in other words, how aggressive your cancer is. It is based on how abnormal your cancer cells and their growth patterns look.
- Low-grade cancer is the least aggressive.
- High-grade cancer is the most aggressive.
Prostate cancers often have areas with different grades. To determine the overall grade of your cancer, your team will look at cells from the two areas that make up most of your cancer, and they’ll assign a Gleason grade to each area. Gleason grades range from 3 to 5.
With a couple of exceptions, the sum of your two Gleason grades is your Gleason score.
- A score of 6 is low grade.
- A score of 7 is intermediate grade.
- A score of 8 to 10 is high grade.
Staging prostate cancer: the TNM system
Staging is done as part of the diagnosis process to determine how extensive your cancer is within your prostate and whether it has spread to lymph nodes or other organs.
Prostate cancer is typically staged using the TNM system, which is based on:
- The extent of the primary tumor (T category)
- Whether the cancer has spread to nearby lymph nodes (N category)
- The presence or absence of distant metastasis (M category)
- Your PSA level at the time of diagnosis
- Your Gleason score and the amount of cancer
Using this information, prostate cancer is then grouped into stages I through IV, with stage I being the least advanced and stage IV being the most advanced.
- Stage I: Cancer is confined to your prostate. Gleason score is 6 or below. PSA level is less than 10.
- Stage II: The tumor is more advanced but does not extend beyond your prostate.
- Stage III: The tumor extends beyond your prostate and may be in a seminal vesicle. Cancer has not spread to lymph nodes.
- Stage IV: The tumor has spread to another part of your body, such as your bladder, rectum, lymph nodes or bones.
Testing for prostate cancer metastasis
After your biopsy, additional tests or imaging may be performed to check for cancer spread, though these are not required in all men with newly diagnosed prostate cancer.
You may need additional tests if you have:
- High PSA levels
- Extensive prostate involvement on biopsy
- High Gleason scores
The tests may include:
- Computed tomography (CT) scans of your abdomen and pelvis
- Bone scans
- Magnetic resonance imaging (MRI) of your pelvis
Many centers, including SCCA, are testing other means of finding cancer spread using new types of positron emission tomography (PET) scans. Sometimes lymph nodes around the prostate may be checked for metastasis in order to design treatment appropriately.
At SCCA and University of Washington Medical Center, a long-term effort has identified cells in the bone marrow that originated from prostate cancer, even in the absence of other evidence of spread. With these and other studies being offered to men with advanced prostate cancer, we hope to find ways to identify men at the highest risk of relapse so this knowledge can inform our treatment recommendations.
What causes prostate cancer?
While the exact cause of prostate cancer is unknown, generally speaking it results from mutations in cell DNA.
- DNA is the chemical that makes up your genes, which control when your cells grow, divide into new cells and die.
- DNA mutations that turn on oncogenes (which help cells grow and divide) or that turn off tumor-suppressor genes (which slow cell division or make cells die when they should) can cause prostate cells to grow abnormally and lead to cancer.
Prostate cancer risk factors
Many factors may contribute to prostate cancer risk. The main risk factors are:
- Age — Although prostate cancer can occur at any age, it is most often found in men over age 50, and more than two-thirds of men diagnosed with the disease are over 65.
- Family history and genetics — A family history of prostate cancer may increase your risk, particularly if you have a number of close relatives who were younger than 60 when they were diagnosed. If your father or brother had prostate cancer, your risk is two to three times greater than if you had no family history of the disease. Learn more about SCCA’s Prostate Cancer Genetics Clinic.
- Race or ethnicity — African-American men are more likely than men of other races to develop prostate cancer. The disease is less common among men of Asian or Hispanic/Latino descent than among those of European descent.
- Nationality or where you live — Prostate cancer is most common in North America, northwestern Europe, Australia and the Caribbean and less common in Asia, Africa and Central and South America. Screening may account for some of this difference; however, lifestyle differences, such as diet, may also be factors.
- Hormone levels — Research suggests that the development of prostate cancer is linked to higher levels of certain hormones, such as testosterone, the main male sex hormone. Testosterone is changed into dihydrotestosterone (DHT) by an enzyme in the body. DHT is important for normal prostate growth but can also cause the prostate to get bigger and may play a role in development of prostate cancer.
Other factors that may affect risk
Although the reasons are unclear, scientists believe diet is a critical factor in prostate cancer risk. A diet high in red meat, dairy foods and calcium and low in fruits and vegetables may play a part. Vitamin E and folic acid are also thought to increase the risk.
Studies have not shown a clear link between obesity and prostate cancer, but in some studies obese men have had a lower risk of getting a low-grade form of the disease but a higher risk of getting more aggressive prostate cancer. Several studies have found that obese men may be at greater risk of having more advanced prostate cancer and of dying from prostate cancer.
Researchers are studying how nutrition may reduce the risk of prostate cancer. They are also studying whether men can reduce their risk through exercise and by taking certain dietary supplements. Read more about the impact of diet and exercise on prostate cancer.
Scientists have also studied whether having an inflamed or enlarged prostate, having a vasectomy, smoking, being exposed to radiation or having a sexually transmitted virus might increase prostate cancer risk. At this time, there is little evidence that these factors contribute to risk.
Learn more about detecting and preventing prostate cancer.
How common is prostate cancer?
Each year about 160,000 men are diagnosed with prostate cancer in the U.S. and about 27,000 die of the disease. Prostate cancer is the third leading cause of cancer death, behind lung cancer and colon cancer, in men in the United States.
The incidence of prostate cancer has nearly doubled over the past 20 years. One possible reason is that, due to a decline in deaths from heart disease, more men are living longer, reaching ages at which the risk of prostate cancer is highest.