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US Pharm. 2012;37(6):43-45.
In the United States, prostate cancer is the most common type of cancer in men irrespective of race or ethnicity.1
Earlier detection of prostate cancer through the prostate-specific
antigen (PSA) test resulted in an upswing in cases from the mid-1980s to
the mid-1990s.2
Until recently, the PSA test was the gold standard as part of
physical examinations for men, especially in those older than 50 years
of age. As of October 2011, however, the U.S. Preventive Services Task
Force (USPSTF) no longer recommends that men older than 50 years
routinely receive PSA testing.3 This is because there is no
consensus that screening for prostate cancer saves lives, and also
because treatment often leads to complications (e.g., impotence and
incontinence). As a result, the decision to undergo prostate cancer
screening now involves weighing the potential risks and benefits of
screening. An active-surveillance approach to deciding when and if
treatment is appropriate may also be considered if the cancer is found
to be progressing. However, there are lifestyle modifications, such as
engaging in vigorous physical activity, that may reduce the risk of
advanced prostate cancer.
Background
According to the American Cancer Society (ACS), about 1 in 6 men will
be diagnosed with prostate cancer during the course of a lifetime, and
about 1 in 36 will die of the disease.4 Most prostate cancers
grow slowly, but in some cases progression is quick. In several
studies, autopsies of older men who died from other diseases revealed
that many of the patients also had undiagnosed prostate cancer.5 According to these studies, as many as 7 to 9 out of 10 patients had prostate cancer by 80 years of age.5
Scientists believe that prostate cancer begins with prostatic
intraepithelial neoplasia (PIN)—microscopic changes in the size and
shape of prostate cells.
Risk Factors and Warning Signs
It is important to identify men with significant risk factors for
prostate cancer. Risk factors include age, race/ethnicity, family
history, and classification of PIN. Age is one of the strongest risk
factors, with a rapid increase in risk after age 50 years.6
Prostate cancer occurs more commonly in African American men and in men
living in North America, northwestern Europe, Australia, and the
Caribbean Islands.6 The risk is almost doubled if a man has a brother or father with prostate cancer, suggesting that there is a genetic component.6 The risk of prostate cancer is higher if a biopsy reveals high-grade (abnormal) PIN.2
Some of the warning signs of prostate cancer include difficulty
urinating, a weak or interrupted urine flow, erectile dysfunction, pain
or discomfort in the pelvic area, and bone pain.7
Screening
Traditionally, prostate cancer screening was recommended to detect
the disease at earlier, asymptomatic stages, when treatment might be
more effective.3 Two tests are used to screen for prostate
cancer. The first test is the digital rectal examination (DRE), in which
the physician checks for lumps in the prostate by inserting a
lubricated, gloved finger into the rectum. Tumors often grow in the area
of the prostate next to the rectum.8 The presence of a hard
or even spot may signal prostate cancer. The second form of evaluation
is a blood test used to detect the amount of PSA protein circulating in
the blood. In general, the higher a patient’s PSA level, the greater the
chance that cancer is present.9 Alone or in combination,
these tests cannot confer a definitive diagnosis of prostate cancer; in
every case, a prostate biopsy is required to make the diagnosis. Other
causes of elevated PSA include benign prostatic hyperplasia (BPH),
prostatitis, and recent prostate biopsy or DRE.10 Ejaculation or strenuous bicycling also can cause a temporary minor increase in PSA.10 It is important to be aware that PSA levels are low in some early-stage prostate cancers.11
The USPSTF’s Review of Evidence
The USPSTF last reviewed the evidence on prostate cancer screening
and made recommendations in 2008. In an effort to update these
guidelines, the USPSTF conducted an exhaustive review of randomized
trials of PSA-based screening, randomized trials and cohort studies of
prostatectomy or radiation therapy versus watchful waiting (using
changes in symptoms to decide whether treatment is needed), and large
observational studies of perioperative harms.3,12 This review
sought to answer four key questions: (1) Does PSA-based screening
decrease prostate cancer–specific or all-cause mortality? (2) What are
the harms of PSA-based screening for prostate cancer? (3) What are the
benefits of treatment of early-stage or screening-detected prostate
cancer? and (4) What are the harms of treatment of early-stage or
screening-detected prostate cancer? See TABLES 1 to 4 for a summary of the evidence.13
The USPSTF concluded that the PSA test was more likely to lead to a
substantial risk than to a benefit. The PSA test cannot differentiate
between aggressive and nonaggressive cancers, which may result in many
men undergoing needless surgery and radiation that expose them to
significant side effects. According to the USPSTF, up to 5 men in 1,000
will die within a month of prostate cancer surgery, and approximately 10
to 70 men will experience dangerous complications.3 At least
200 of every 1,000 men treated with radiation or surgery will
experience impotence, urinary incontinence, or bowel dysfunction.3
The USPSTF considers these to be serious risks, considering that its
review found that PSA screening has not been proven to save lives.
Other Opinions
The USPSTF has determined that PSA-based screening is associated with
detection of more prostate cancers, results in little reduction in
prostate cancer mortality, and may lead to harms (related to
false-positive test results and subsequent treatment).3 The
largest clinical studies the USPSTF has examined so far have not found a
statistically significant reduction in deaths from prostate cancer
among men who had the PSA test compared with those who did not.
Not all experts agree with the USPSTF’s recommendations, however;
many support an approach of active surveillance. This involves closely
monitoring for cancer via screening tests at regular intervals and then
considering treatment options if test results indicate cancer
progression.12
Shortly after the USPSTF released its report, the American Urological
Association (AUA) issued a statement in response. The AUA’s stance is
that an appropriately interpreted PSA test provides important
information concerning the diagnosis, pretreatment staging or risk
assessment, and monitoring of prostate cancer patients.14 The
AUA recommends that once a diagnosis of prostate cancer is made, the
patient should discuss with his urologist whether active surveillance or
treatment is appropriate.14 This is because not all prostate cancers require treatment, and not all are life-threatening.14
The ACS also recommends that a patient consult his physician,
consider the risks and benefits, and make an informed decision about
whether to be screened for prostate cancer.15
Lifestyle Modifications
Even if a patient decides against being screened for prostate cancer,
there are lifestyle modifications that can help reduce the risk of
advanced or lethal disease. Most older men have prostate cancer, but the
type of prostate cancer is what is significant.2 The most
promising lifestyle modification to lower the risk of advanced disease
is to increase the amount of physical activity. A 2005 study found that
older men who engaged in vigorous activities such as jogging, biking,
swimming, or tennis had a 70% lower risk of advanced or lethal cancer.16 Even though staying lean does not cut the risk of being diagnosed with prostate cancer, it may decrease mortality.17 A healthy body weight at or before diagnosis is a strong predictor of survival.2
Additionally, the benefits of exercising and losing weight go beyond
decreasing the risk of prostate cancer. Studies examining the effect of
taking vitamin E, selenium, lycopene, vitamin D, or calcium have
conflicting results; therefore, no definitive conclusion concerning the
effect of these lifestyle modifications can yet be made.18-22
Conclusion
Because it detects prostate cancer earlier, the PSA test has been
routinely performed as part of a man’s physical examination. Based on a
comprehensive review of evidence, the USPSTF has concerns about PSA
testing and no longer recommends routine screening; however, the AUA and
other experts disagree. Patients should discuss the risks and benefits
of PSA screening with their physician and make an informed decision.
REFERENCES
1. CDC. Prostate cancer: fast facts. www.cdc.gov/cancer/prostate/basic_info/fast_facts.htm. Accessed February 22, 2012.
2. Center for Science in the Public Interest. Cancer—how to lower your risk. Nutrition Action HealthLetter. January/February 2012:3-7.
3. U.S. Preventive Services Task Force. Screening for prostate
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www.uspreventiveservicestaskforce.org/uspstf12/prostate/prostateart.htm.
Accessed February 22, 2012.
4. American Cancer Society. What are the key statistics about
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5. American Cancer Society. What is prostate cancer?
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www.cancer.org/Cancer/ProstateCancer/DetailedGuide/prostate-cancer-risk-factors.
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www.uspreventiveservicestaskforce.org/uspstf12/prostate/prostatearttab1.htm.
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and tocopherols and the risk of prostate cancer in the European
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22. Albanes D, Mondul AM, Yu K, et al. Serum 25-hydroxy vitamin D and
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