Prostate cancer begins when cells in the prostate gland start to grow uncontrollably. The prostate is a gland found only in males. It makes some of the fluid that is part of semen.
The prostate is below the bladder and in front of the rectum. The size of the prostate changes with age. In younger men, it is about the size of a walnut, but it can be much larger in older men.
Just behind the prostate are glands called seminal vesicles that make most of the fluid for semen. The urethra, which is the tube that carries urine and semen out of the body through the penis, goes through the center of the prostate.
Signs and symptoms of prostate cancer
Early prostate cancer usually causes no symptoms. More advanced prostate cancers sometimes cause symptoms, such as:
- Problems urinating, including a slow or weak urinary stream or the need to urinate more often, especially at night
- Blood in the urine or semen
- Trouble getting an erection (erectile dysfunction)
- Pain in the hips, back (spine), chest (ribs), or other areas from cancer that has spread to bones
- Weakness or numbness in the legs or feet, or even loss of bladder or bowel control from cancer pressing on the spinal cord
Most of these problems are more likely to be caused by something other than prostate cancer. For example, trouble urinating is much more often caused by benign prostatic hyperplasia (BPH), a non-cancerous growth of the prostate. Still, it’s important to tell your doctor if you have any of these symptoms so that the cause can be found and treated, if needed.
Prostate cancer risk factors
A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.
But having a risk factor, or even several, does not mean that you will get the disease. Many people with one or more risk factors never get cancer, while others who get cancer may have had few or no known risk factors.
Researchers have found several factors that might affect a man’s risk of getting prostate cancer.
Prostate cancer is rare in men younger than 40, but the chance of having prostate cancer rises rapidly after age 50. About 6 in 10 cases of prostate cancer are found in men older than 65.
Prostate cancer occurs more often in African-American men and in Caribbean men of African ancestry than in men of other races. African-American men are also more than twice as likely to die of prostate cancer as white men. Prostate cancer occurs less often in Asian-American and Hispanic/Latino men than in non-Hispanic whites. The reasons for these racial and ethnic differences are not clear.
Prostate cancer is most common in North America, northwestern Europe, Australia, and on Caribbean islands. It is less common in Asia, Africa, Central America, and South America.
The reasons for this are not clear. More intensive screening in some developed countries probably accounts for at least part of this difference, but other factors such as lifestyle differences (diet, etc.) are likely to be important as well. For example, Asian Americans have a lower risk of prostate cancer than white Americans, but their risk is higher than that of men of similar backgrounds living in Asia.
Prostate cancer seems to run in some families, which suggests that in some cases there may be an inherited or genetic factor. (Still, most prostate cancers occur in men without a family history of it.)
Having a father or brother with prostate cancer more than doubles a man’s risk of developing this disease. (The risk is higher for men who have a brother with the disease than for those who have a father with it.) The risk is much higher for men with several affected relatives, particularly if their relatives were young when the cancer was found.
Several inherited gene changes seem to raise prostate cancer risk, but they probably account for only a small percentage of cases overall. For example:
- Inherited mutations of the BRCA1 or BRCA2 genes raise the risk of breast and ovarian cancers in some families. Mutations in these genes (especially in BRCA2) may also increase prostate cancer risk in some men.
- Men with Lynch syndrome (also known as hereditary non-polyposis colorectal cancer, or HNPCC), a condition caused by inherited gene changes, have an increased risk for a number of cancers, including prostate cancer.
Other inherited gene changes can also raise a man’s risk of prostate cancer. For more on some of these gene changes, see What causes prostate cancer?.
Factors with less clear effect on prostate cancer risk
The exact role of diet in prostate cancer is not clear, but several factors have been studied.
Men who eat a lot of red meat or high-fat dairy products appear to have a slightly higher chance of getting prostate cancer. These men also tend to eat fewer fruits and vegetables. Doctors aren’t sure which of these factors is responsible for raising the risk.
Some studies have suggested that men who consume a lot of calcium (through food or supplements) may have a higher risk of developing prostate cancer. Dairy foods (which are often high in calcium) might also increase risk. But most studies have not found such a link with the levels of calcium found in the average diet, and it’s important to note that calcium is known to have other important health benefits.
Being obese (very overweight) does not seem to increase the overall risk of getting prostate cancer.
Some studies have found that obese men have a lower risk of getting a low-grade (less dangerous) form of the disease, but a higher risk of getting more aggressive prostate cancer. The reasons for this are not clear.
Some studies have also found that obese men may be at greater risk for having more advanced prostate cancer and of dying from prostate cancer, but not all studies have found this.
Most studies have not found a link between smoking and getting prostate cancer. Some research has linked smoking to a possible small increased the risk of dying from prostate cancer, but this finding needs to be confirmed by other studies.
There is some evidence that firefighters can be exposed to chemicals that may increase their risk of prostate cancer.
A few studies have suggested a possible link between exposure to Agent Orange, a chemical used widely during the Vietnam War, and the risk of prostate cancer, although not all studies have found such a link. The Institute of Medicine considers there to be “limited/suggestive evidence” of a link between Agent Orange exposure and prostate cancer. To learn more, see Agent Orange and Cancer.
Inflammation of the prostate
Some studies have suggested that prostatitis (inflammation of the prostate gland) may be linked to an increased risk of prostate cancer, but other studies have not found such a link. Inflammation is often seen in samples of prostate tissue that also contain cancer. The link between the two is not yet clear, and is an active area of research.
Sexually transmitted infections
Researchers have looked to see if sexually transmitted infections (like gonorrhea or chlamydia) might increase the risk of prostate cancer, because they can lead to inflammation of the prostate. So far, studies have not agreed, and no firm conclusions have been reached.
Some studies have suggested that men who have had a vasectomy (minor surgery to make men infertile) have a slightly increased risk for prostate cancer, but other studies have not found this. Research on this possible link is still under way.
American Cancer Society ACS
PROSTATE CANCER SCREENING
Prostate cancer screening is controversial. On one hand, detecting prostate cancer early may allow for more treatment options with potentially fewer side effects. On the other hand, because most prostate cancers grow slowly, the side effects of treatment may outweigh any of the benefits of early detection.
Because prostate cancer does not typically cause symptoms until advanced stages, two tests are currently used to detect the disease at earlier stages.
The first is the Prostate-Specific Antigen (PSA) Test. PSA is a protein produced by the prostate gland. The PSA test measures levels of PSA in blood, with a higher PSA level indicating a greater likelihood of prostate cancer.
The second test is a Digital Rectal Exam (DRE). In this exam, a doctor inserts a gloved finger into the rectum to feel for hard, lumpy, or abnormal areas on the prostate.
False-positives may occur in both of these tests. There is much evidence that PSA and DRE are best used together. As the PSA increases, the positive predictive value of the DRE also increases.
Research on prostate cancer screening effectiveness reaches mixed conclusions. Two large randomized trials investigated the usefulness of screening men for prostate cancer with the PSA blood test. The first trial was conducted in the US and explored whether intensive (frequent) screening was more effective than opportunistic (in-frequent) screening at saving lives. The second trial was conducted across multiple countries in Europe and examined whether intensive screening was better than no screening at all. The US study did not find intensive screening to be better than opportunistic screening. However, it did find that intensive screening reduced prostate cancer related deaths in healthy men under age 65. Conversely, the European study found that intensive screening reduced prostate cancer mortality by 20-28%. Importantly, the European study showed that this effect was most pronounced in Northern European countries including Sweden, Netherlands and Finland.
SPECIAL PROSTATE ALERT: PSA CONTROVERSY
by Patrick C. Walsh, M.D., University Distinguished Service Professor of Urology
What is the take home message?
If you are the kind of person who doesn’t wear a seat belt nor goes regularly to the dentist or your family doctor for a check-up and are not worried about dying from prostate cancer, do not undergo PSA testing. On the other hand if you are a healthy man age 55-69 who does not want to die from prostate cancer, the European trial provides conclusive evidence that PSA testing can save your life.
Recommendations on when to Start Screening
The American Urology Association (auanet.org) recommends:
Discussions about PSA screening and shared decision making about screening should begin at age 55. The AUA suggests that the greatest benefit of PSA screening is in men aged 55-69.
Individualized Prostate cancer screening for men under the age of 55 with a family history or of african descent.
For additional details please see: https://www.auanet.org/education/guidelines/prostate-cancer-detection.cfm
Prostate cancer screening is performed with a PSA blood test and a rectal exam.
The American Cancer Society (acs.org) recommends discussions about screening should begin at:
- Age 50 for men who are at average risk of prostate cancer and are expected to live at least 10 more years.
- Age 45 for men at high risk of developing prostate cancer. This includes African Americans and men who have a first-degree relative (father, brother, or son) diagnosed with prostate cancer at an early age (younger than age 65).
- Age 40 for men at even higher risk (those with more than one first-degree relative who had prostate cancer at an early age).
The American Cancer society recommends that Prostate cancer screening be performed annually if the PSA value is over 2.5 and every other year if the test is less than 2.5.
The American Cancer society does not recommend screening men who have a life expectancy of less than 10 years.
For additional details please see:http://www.cancer.org/cancer/prostatecancer/moreinformation/prostatecancerearlydetection/prostate-cancer-early-detection-acs-recommendations
Please read New Options for Prostate Cancer Screening
Prostate cancer is the most common cancer among men of all races and Hispanic* origin populations. Women and men need to find a health care provider they are comfortable with and will see on a regular basis. Establishing a relationship with a consistent health care provider can move you in the direction of health and wellness. In regards to test results and screenings, remember that information you receive is valuable and “knowledge is power”. How you decide to use information is up to you in consultation with reputable health care providers and your family.
See a primary care physician regularly and men please start PSA screening at age 50. If you are at high risk for prostate cancer (i.e. family relative such as father or brother with PC) start PSA screening at 35.