Overview
Prostate cancer is the second-leading cause of cancer deaths among men in the United States and a significant health-care problem due to its high incidence. It is estimated that in the United States (U.S.), there will be more than 240,890 new cases and 33,720 deaths from prostate cancer in 2011. The natural history and progression of this disease is not completely understood. An analysis of autopsy studies has shown that approximately one in three men over the age of 50 had histologic evidence of prostate cancer, with up to 80 percent of these tumors being limited in size and grade and, therefore, clinically insignificant. However, a recent study of incidental prostate cancer in organ donors found it in 1 in 3 men age 60-69, and this increased to 46 percent in men over age 70.
The number of men diagnosed with prostate cancer remains high. However, five-year relative survival rates have increased dramatically over the years. There also has been at least a 25 percent reduction in the age-specific prostate cancer mortality rate since the beginning of the PSA era. It is estimated that 99 percent of men diagnosed with localized or regional prostate cancer survive at least five years, while only 33 percent of those with metastases at diagnosis survive five years.
For African American men, however, the statistics are more dramatic. African American men are more likely to be diagnosed at a later stage, and 2.4 times more likely than white men to die of prostate cancer. For individuals with a family history, the risk is even higher.
The prostate is part of the male reproductive system and is a small, walnut-sized gland below the bladder and in front of the rectum. The prostate gland secretes a fluid that makes up part of the semen.
Men should discuss prostate screening with their physicians, as this can help maintain proper prostate health.
Causes
The precise cause of prostate cancer is still unknown; however, the scientific community is conducting research and hopes to find the answer soon. The current theory is there are many factors that can increase a man’s risk for prostate cancer. The following are some known factors:
- Age
- Smoking
- World Region Location
- Ethnicity – being African American doubles your risk
- Family History
- Diet
- Vasectomy
- Vitamins
The disease predominately affects older men, and is rarely found in men younger than age 40. Approximately one in 35 men will die of prostate cancer, and African Americans are twice as likely as Caucasian men to die of the disease. According to the American Cancer Society, prostate cancer accounts for about 10 percent of cancer-related deaths in men between the ages of 60 and 79, and nearly 25 percent in those over the age of 80.
As men age, the risk of developing prostate cancer increases. For heavy smokers, studies have shown that the risk of prostate cancer may be double. The good news is, the risk decreases to roughly that of a non-smoker of the same age within 10 years of quitting.
Worldwide, prostate cancer ranks third in cancer incidence and sixth in cancer mortality among men. There is a notable variability in incidence and mortality among world regions. The incidence is low (but rapidly increasing) in Japan and other Asian countries, and intermediate in regions of Central America and Western Africa. The incidence is higher in North America and Northern Europe. The higher rates in North America and Northern Europe could be due to different screening practices, genetic predisposition, diet, and environmental factors.
African-Americans are in the highest risk group, with an incidence of more than 200 cases per 100,000 black men. While the incidence in Caucasian and Asian men is slightly more than half that of blacks, African-American men tend to present 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; having more first-degree relatives with a history of prostate cancer increases a man’s risk. The age at which first-degree relatives were diagnosed can also affect the risk. Men with a family history of disease are two to eleven times more likely to develop prostate cancer than men without a family history of prostate cancer.
There is also considerable evidence showing a Western lifestyle is associated with increased prostate cancer risk and increased death from prostate cancer. However, the specific lifestyle factors are unknown. Engaging in excessive calorie, dietary fat, and refined sugar intake with reduced fruits, vegetables, and exercise is shown to increase the risk of prostate cancer, though the relationship is not entirely clear. The most commonly cited dietary risk factor is a high intake of dietary fat. Being obese is associated with an increased risk for death from prostate cancer. Thus, the simplest advice for avoiding death from prostate cancer is to prevent obesity, or to lose weight and maintain a healthy weight if you are obese.
There is a limited amount of evidence to suggest that the worldwide difference in prostate cancer incidence may be associated with the increased intake of soy proteins in other parts of the world. In Asian countries where prostate cancer incidence and mortality are just a fraction of that in North America, such as Japan and the Republic of Korea, soy consumption in the form of tofu, soy milk and miso is up to 90 times higher than that of the United States. In a study of more than 40 nations, researchers found soy, on a per calorie basis, to be the most protective dietary factor. This protective role may be associated with two of soy’s components, genistein and daidzein, that may act as weak estrogens. Estrogens are female hormones that inhibit prostate cancer growth. Some experts have suggested that the worldwide differences in prostate cancer incidence may also be explained by the high intake of green tea by residents of Asia. However, determining which dietary factors affect prostate cancer is not easy, and no clear answers have emerged.
It is suggested that lycopene, fish oil, and other substances may also reduce the risk of developing prostate cancer. Cooked tomatoes are rich sources of lycopene. Lycopenes are antioxidants that may protect cells from becoming cancerous. Several studies have shown that the likelihood of developing prostate cancer is reduced by high intake of lycopene. Researchers found that men ingesting two or more servings of tomato sauce per week had a 36 percent reduction in cancer risk compared to those who did not, though not all studies have supported this.
Fish oils (omega-3 fatty acids) are thought to reduce heart disease by reducing inflammation. Because inflammation is thought to contribute to prostate cancer, it stands to reason that fish oils may prevent prostate cancer. Indeed, some studies have suggested this, though others have failed to find any link.
The correlation of vasectomy and prostate cancer risk remains controversial. Although some studies have suggested that men who have undergone a vasectomy are at an increased risk of developing prostate cancer, many other studies have failed to show such a correlation.
Attention has also focused on vitamin D’s effect on the prostate. Epidemiologic evidence shows an inverse relationship between prostate cancer risk and ultraviolet radiation, the primary source for vitamin D production. This observation has led some to suggest that higher rates of prostate cancer in the elderly may be partly due to decreased sun exposure or a decline in the body’s ability to make vitamin D. However, several recent studies have found no correlation between vitamin D levels and prostate cancer risk, and one even found that men with increased vitamin D had a higher risk of aggressive prostate cancer!
Finally, a word of caution is needed. Based upon very exciting data, the National Institute of Health embarked a large randomized trial of over 30,000 men to test whether vitamin E or selenium would prevent prostate cancer. Unfortunately, the trial was stopped early because there was no evidence either agent alone or in combination prevented prostate cancer. Moreover, there was a suggestion that men who took vitamin E had an increased risk of prostate cancer and men who took selenium had a slightly higher risk of diabetes! This highlights the point that there is no easy substitute for a healthy lifestyle involving eating a balanced diet, avoiding dietary excesses, eating plenty of fruits and vegetables, getting lots of exercise, and most importantly achieving and maintaining a normal body weight.
While most doctors agree that there are no exact causes of prostate cancer, a general rule of thumb is that habits that keep your heart healthy will also help keep your prostate healthy. Eating right, exercising, watching your weight, and not smoking can improve your health and possibly help you avoid this disease.
Symptoms
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;
- persistent bone pain
Treatments
Currently, digital rectal examination (DRE) and prostate specific antigen (PSA) are used for prostate cancer detection. The American Urological Association recommends that healthy men over the age of 40 should consider obtaining a baseline prostate cancer screening with a DRE and PSA test. Evidence from research studies suggest that combining both tests improves the overall rate of prostate cancer detection.
DRE: the DRE is performed with the man either bending over, lying on his side or with his knees drawn up to his chest on the examining table. The physician inserts a gloved finger into the rectum and examines the prostate gland, noting any abnormalities in size, contour, or consistency. DRE is inexpensive, easy to perform and allows the physician to note other abnormalities such as blood in the stool or rectal masses, which may allow for the early detection of rectal or colon cancer. Because the DRE by itself is not an effective way to detect early cancer, it should always be combined with a PSA test.
Prostate Specific Antigen Test (PSA): the PSA test is usually performed in addition to DRE and increases the likelihood of prostate cancer detection. The test measures the level of PSA, a substance produced only by the prostate, in the bloodstream. The blood test can be done in a clinical laboratory, hospital, or physician’s office, and requires no special preparation on the part of the patient. Ideally, the test should be taken before a DRE is performed or any catheterization or instrumentation of the urinary tract. Furthermore, because ejaculation can transiently elevate the PSA level for 24 to 48 hours, the patient should abstain from sexual activity for two days prior to having a PSA test.
Very little PSA is detected from patients with a healthy prostate, but certain prostatic conditions can cause larger amounts of PSA to leak into the blood. One possible cause of a high PSA level is benign (non-cancerous) enlargement of the prostate, otherwise known as BPH. Inflammation of the prostate, called prostatitis, is another common cause of PSA elevation, as is recent ejaculation. Prostate cancer is the most serious possible cause of an elevated PSA level. The recommended frequency of PSA testing remains a matter of some debate.
The American Urological Association (AUA) believes that the decision to screen is one that a man should make with his doctor, following a careful discussion of the benefits and risks of screening. In men who wish to be screened, the AUA recommends getting a baseline PSA, along with a physical exam of the prostate known as a digital rectal exam (DRE) at age 40. A disadvantage of infrequent testing is that it limits the ability to detect a rapidly rising PSA levels that can signal aggressive prostate cancer, though this is relatively uncommon for men with such low PSA values. Recently, several refinements have been made in the PSA blood test in attempts to determine more accurately who has prostate cancer and who has false positive PSA elevations caused by other conditions like BPH. These refinements include PSA density, PSA velocity, PSA age-specific reference ranges and use of free-to-total PSA ratios. Such refinements may increase the ability to detect cancer and these should be discussed with your physician.
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 or prostatitis.
What happens if my PSA and/or DRE are abnormal?
If you have an abnormal prostate cancer screening, the only way to determine if you have, prostate cancer is through a biopsy. The decision to proceed with a prostate biopsy should be based primarily on PSA and DRE results. It should also take into account other factors, including family history of prostate cancer, race, any prior biopsy history, and other significant health issues you may have. A prostate biopsy is best performed under transrectal ultrasound guidance using a spring-loaded biopsy device coupled to the transrectal probe.
Patients are positioned on their side for this procedure, and are given an enema and an antibiotic. The lubricated ultrasound probe is inserted into the rectum. The physicians will first us the ultrasound to find the prostate gland, particularly focusing on the size, shape, and whether or not any other abnormalities are present. The most common abnormalities are shadows, which might signify the presence of prostate cancer. However, not all prostate cancers are visible. After the prostate gland has been anesthetized with an injection of a local anesthetic through a long fine needle that is passed through the probe, the physician performs the biopsy. Using the spring-loaded biopsy device attached to the ultrasound probe, the physician removes several pieces of the prostate gland. Generally, 10 to 12 pieces or cores are removed (or more, depending upon the size of the prostate gland and the prior PSA and biopsy history of the patient). Each core of prostate tissue is approximately 3/4 inch in length and 1/16 inch in width. The entire procedure takes 20 to 30 minutes. The removed tissue is taken and will be examined by a pathologist, a physician who specializes in examining human tissue to determine whether it is normal or diseased. 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 degree of aggressiveness—how quickly it is likely to grow and spread.
The transrectal ultrasound-guided prostate biopsy is usually well-tolerated. Local anesthetics help to minimize the discomfort associated with the biopsy. There are some side effects that may result from the biopsy, such as, blood in the ejaculate (hematospermia) and/or blood in the urine (hematuria). High fever is rare, occurring in only one to two percent of patients. The antibiotic is continued for at least 48 hours after the biopsy procedure
How does the Gleason Score work?
The Gleason grading system is the most widely used system for grading cancer severity. Because several different tumor patterns are often seen, the most common tumor pattern is assigned a score from 1 to 5 and the second most common pattern is also assigned a score. The two scores are added together to give a Gleason sum ranging between 2 and 10. Scores of 2 to 6 designate mildly aggressive prostate cancer, 7 moderately aggressive and scores of 8 to 10 are highly aggressive cancers.
How is prostate cancer staged?
Once prostate cancer has been diagnosed by a prostate biopsy, the physician must stage the disease. Staging the disease determines the extent of the cancer (i.e., the “T” stage) and whether the cancer has spread from the prostate to other tissues such as the seminal vesicles, the lymph nodes, and/or the bones. The T stage is determined by using the DRE and other imaging procedures like the ultrasound scan, CT scan, MRI scan, or MR spectroscopy scan.
The T stage is divided into the following categories:
T1: Doctor is unable to feel the tumor
T1a: Cancer is found incidentally during a transurethral resection (TURP) for benign prostatic enlargement. Cancer is present in less than 5% of the tissue removed and is low grade (Gleason < 6)
T1b: Cancer is found after TURP but is present in more than 5% of the tissue removed or is of a higher grade (Gleason > 6)
T1c: Cancer is found by needle biopsy that was done because of an elevated PSA
T2: Doctor can feel the tumor when a digital rectal exam (DRE) is performed but the tumor still appears to be confined to the prostate
T2a: Cancer is found in one half or less of only one side (left or right) of the prostate
T2b: Cancer is found in more than half of only one side (left or right) of the prostate
T2c: Cancer is found in both sides of the prostate
T3: Cancer has begun to spread outside of the prostate and may involve the seminal vesicles
T3a: Cancer extends outside the prostate but not to the seminal vesicles
T3b: Cancer has spread to the seminal vesicles
T4: Cancer has spread to adjacent organs, such as the urethral sphincter, rectum, bladder, and/or wall of the pelvis
Imaging tests, such as radionuclide bone scan, CT scan, MRI, and MR spectroscopy may help assess whether the cancer is still confined to the prostate or spread elsewhere. To determine if the cancer has spread to the lymph nodes or bones, the physician may order a CT or MRI scan of the pelvis. Sometimes follow-up images are needed to evaluate abnormalities found on the bone scan. These tests are not recommended for men with a Gleason grade lower than 7 and a PSA level lower than 10 ng/ml, as they rarely show disease.
How do I determine which treatment option is best for me?
Prostate cancer represents a spectrum of disease. Some cancers may grow so slowly that treatment may not be needed, while others grow fast and are life threatening. Determining the need for treatment can be a complex decision. Initially, the need for treatment should be based on the stage and grade of the cancer, as well as the age and health of the patient.
Many physicians have sought to devise risk assessment tools that predict the likelihood of disease recurrence and progression. By combining many types of information (e.g., serum PSA level, clinical stage, Gleason score, extent of cancer in biopsy specimens), patients can be advised of the likely aggressiveness of their cancer, the need for treatment, and types of treatment available. However, the longer the patient’s life expectancy, the more uncertain the prediction becomes, as most prostate cancers progress with time.
When prostate cancer spreads (metastasizes) it usually progresses by first perforating the capsule and extending into the periprostatic tissues, then extending to the seminal vesicles, then to the lymph nodes and, finally, to the bones, lungs, and other organs.
FAQ
Are there tests to determine if my cancer has metastasized?
To determine if your cancer has spread to other parts of your body your doctor may recommend the following:
- A pelvic CT scan
- MRI scan
- Bone scan
Not all men with prostate cancer need to undergo imaging tests, as the risk of spreading to other organs can be estimated by PSA levels and cancer grade. It is also standard to omit the bone scan in the following patients:
- Newly diagnosed, untreated prostate cancer,
- Patients who have no symptoms from their cancer,
- Gleason score of less than 7 and have serum PSA concentrations less than 10 ng/ml
- PSA concentrations less than 15 ng/ml (unless the Gleason score is 7 or higher)
A pelvic CT scan or MRI may not be necessary in lower grade cancers, cancers still confined to the prostate, and serum PSA values less than 10 ng/ml.
Can prostate cancer be prevented?
There is still a lot of controversy regarding the prevention of prostate cancer. Some physicians believe anti-androgen drugs, such as finasteride and dutasteride, can prevent prostate cancer. Others are skeptical, and believe anti-androgens only slow the progression of well-differentiated tumors while allowing higher-grade elements to emerge as the dominant elements in the tumor. In randomized trials, men taking these drugs were less likely to be diagnosed with prostate cancer. However, whether the drugs affect the cancer’s aggressiveness and translate into a lower death risk is still unknown. Some physicians believe that general health measures might reduce the risk of prostate cancer, such as eating and maintaining a normal body weight, a healthy diet, being physically active, and visiting the doctor on a regular basis. However, the best practice to prevent prostate cancer is to live and practice a healthy lifestyle.
What are the current treatment options for localized prostate cancer?
Because not all prostate cancer is the same and not all are life threatening, the treatment options you choose should be very specific to your personal health history. It is an individual decision that each patient should make with his doctor and family. No one treatment is perfect for every man.
Several factors come into play when selecting the best treatment for an individual:
- Tumor stage (extent of local spread) and grade (aggressiveness);
- PSA level (higher levels indicating a greater risk of cancer recurrence after treatment), and extent of disease (number of biopsy cores with cancer);
- Competing medical co-morbidities (other diseases that can affect life expectancy);
- Age at diagnosis. As most prostate cancers take many years to become evident and cause morbidity, the same tumor in an older man may pose a lower risk of causing problems in his lifetime
It is important that you speak to your doctor about which treatment is right for you. Below is a list of the common medical treatments for localized prostate cancer:
- Active Surveillance
- Surgery
- Radiotherapy
- Cryotherapy
Active Surveillance
What is Active Surveillance?
Prostate cancer is often a slow progressive disease, and many men with prostate cancer will die from causes other than prostate cancer. Your physician may recommend active surveillance as a treatment option if you have been diagnosed with a very early stage of prostate cancer.