Prostate cancer is the most common cancer among men (after skin cancer), but it can often be treated successfully. More than 2 million men in the U.S. count themselves as prostate cancer survivors.
The prostate is a gland found only in males. It is located in front of the rectum and below the urinary bladder. The size of the prostate varies with age. In younger men, it is about the size of a walnut, but it can be much larger in older men.
The prostate's job is to make some of the fluid that protects and nourishes sperm cells in semen, making the semen more liquid. 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.
Types of Prostate Cancer
Several types of cells are found in the prostate, but almost all prostate cancers develop from the gland cells. Gland cells make the prostate fluid that is added to the semen. The medical term for a cancer that starts in gland cells is adenocarcinoma.
Other types of cancer can also start in the prostate gland, including sarcomas, small cell carcinomas, and transitional cell carcinomas. But these types of prostate cancer are so rare that if you have prostate cancer it is almost certain to be an adenocarcinoma.
The causes of prostate cancer are still not completely understood, but researchers have found several factors that might change the risk of getting it.
- Age: Prostate cancer is very 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 over the age of 65.
- Race/ethnicity: Prostate cancer occurs more often in African-American men and Jamaican men of African ancestry than in men of other races. 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.
- Nationality: 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.
- Family history: Prostate cancer seems to run in some families, which suggests that in some cases there may be an inherited or genetic factor. Having a father or brother with prostate cancer more than doubles a man's risk of developing this disease. The risk is much higher for men with several affected relatives, particularly if their relatives were young at the time the cancer was found.
- Diet: 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.
- Obesity: Most studies have not found that being obese (very overweight) is linked with a higher risk of getting prostate cancer overall.
Screening for Prostate Cancer
Prostate cancer can often be found early by testing the amount of prostate-specific antigen (PSA) in a man's blood. Another way to find prostate cancer is the digital rectal exam (DRE), in which the doctor puts a gloved finger into the rectum to feel the prostate gland.
If the results of either one of these tests are abnormal, further testing is needed to see if there is a cancer. If prostate cancer is found as a result of screening with the PSA test or DRE, it will probably be at an earlier, more treatable stage than if no screening were done.
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. This discussion about screening should take place:
- At age 50 for men who are at average risk of prostate cancer and are expected to live at least 10 more years.
- Starting at age 45 for men at high risk of developing prostate cancer. This includes African-American men and men who have a first-degree relative (father, brother, or son) diagnosed with prostate cancer at an early age (younger than age 65).
- At age 40 for men at even higher risk (those with more than one first-degree relative who had prostate cancer at an early age).
Assuming 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 less than 2.5 ng/ml 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.
- American Cancer Society
- Centers for Disease Control and Prevention (CDC)
- National Cancer Institute at the National Institutes of Health