Prostate cancer is the second leading cause of cancer deaths among men in the United States. When detected in its early stages, prostate cancer can be effectively treated and cured.
What Is The Prostate?
The prostate gland is a small, walnut-sized gland in men. It is located below the bladder and surrounds the upper portion of the urethra. The prostate gland lies in front of the rectum, and its posterior surface can be felt during a rectal examination. The function of the prostate is to secrete a fluid that makes up part of the semen. The prostate gland may be a source of health problems in men, the more common being benign prostatic hyperplasia (BPH), prostatitis and prostate cancer.
Prostate cancer is a significant health-care problem in the United States due to its high incidence. It is the most common cancer affecting American men. Prostate cancer is different from most cancers in that a large percentage of men may have a silent form of this disease. Sometimes this cancer can be small, slow growing and presents limited risk to the patient. Clinically important prostate cancers can be defined as those that threaten the well-being or life span of a man.
Causes And Risks
What causes prostate cancer is a subject of intensive research. It is likely that prostate cancer occurs due to many reasons. Predominately a disease of older men, the diagnosis of prostate cancer is rare before age 40 but increases dramatically thereafter. In the United States, it is estimated that one in 55 men between the ages of 40 and 59 will develop prostate cancer. This incidence climbs almost to one in seven for men between ages 60 and 79.
Worldwide, prostate cancer ranks third in cancer incidence and sixth in cancer mortality among men. There is, however, a notable variability in incidence and mortality among world regions. The incidence is low in Japan and intermediate in regions of Central America and Western Africa. The incidence is higher in North America and Northern Europe. Although some of these differences may be accounted for by differences in screening for prostate cancer and the risk of other diseases among world regions, it is likely that they can be accounted for, in part, by genetic predisposition as well as diet.
There are also ethnic determinants of risk. Blacks are in the highest risk group, the incidence in Caucasian and Asian men is considerably lower. In addition, blacks tend to present with more advanced disease and have poorer overall prognosis than Caucasian or Asian men.
Men with a family history of prostate cancer are at an increased risk of developing the disease. The risk correlates with the number of first-degree relatives (father, brother or uncle) affected by prostate cancer and the age at onset. Men with a family history of disease may have a risk of developing prostate cancer two to 11 times greater than men without a family history of prostate cancer. There is also considerable evidence showing that prostate cancer is more common in men with a high intake of fat in their diets. Vitamin D deficiency may predispose men to prostate cancer. Conversely, a diet rich in soy, tofu and green tea may protect against prostate cancer.
In its early stages, prostate cancer often causes no symptoms. When symptoms do occur, they may include any of the following: dull pain in the lower pelvic area; frequent urination; problems with urination such as the inability, pain, burning, weakened urine flow; blood in the urine or semen; painful ejaculation; general pain in the lower back, hips or upper thighs; loss of appetite and/or weight; and persistent bone pain.
Currently, digital rectal examination (DRE) and PSA tests are used for prostate cancer detection. The age at which time screening for prostate cancer should begin is not known with certainty. However, most experts agree that healthy men over the age of 50 should consider prostate cancer screening with a DRE and PSA test. Screening should occur earlier, at age 45, in those who are at a higher risk of prostate cancer such as black men or those with a family history of prostate cancer.
Currently, it is recommended that both a DRE and PSA test be used for the early detection of prostate cancer. It is important to realize that in most cases an abnormality in either test is not due to cancer but to benign conditions, the most common being BPH. For instance, it has been shown that only 18 to 30 percent of men with serum PSA values between four and 10 ng/ml have prostate cancer. This number rises to approximately 42 to 70 percent for those men whose PSA values exceeding 10 ng/ml.
Prostate biopsy is best performed under transrectal ultrasound guidance using a spring-loaded biopsy device coupled to the transrectal probe, which is placed in the rectum. Patients are positioned on their side for this procedure. The physician will first image the prostate using ultrasound noting the prostate gland's size and shape and whether or not any other abnormalities exist, the most common of which are shadows which might signify the presence of prostate cancer. However, not all prostate cancers are visible. The entire procedure will take 20 to 30 minutes. The biopsy tissue taken will then be examined by a pathologist. The pathologist will be able to confirm if cancer is present in the biopsy tissue. If cancer is present, the pathologist will also be able to grade the tumor. The grade indicates the tumor's "aggression level" — how quickly it is likely to grow and spread. The most popular prostate cancer grading system is the Gleason score system and is designated between two and 10. Scores of two to four designate low aggressiveness, five to six mildly aggressive, seven moderately aggressive and scores of eight to 10 highly aggressive.
Although transrectal ultrasound guided prostate biopsy is usually very well tolerated, approximately 20 to 25 percent of those undergoing the procedure may find it painful. Injecting local anesthetics into the area before biopsy may minimize this discomfort. Blood in the ejaculate (hematospermia) and blood in the urine (hematuria) are common, occurring in approximately 40 to 50 percent of patients. High fever is rare, occurring in only 3 to 4 percent of patients. Antibiotics and enemas are usually given at the time of the procedure to prevent infection.