- Engage patients in shared decision making by discussing the benefits and risks of prostate cancer screening. Patients who review educational pamphlets before an office visit engage more fully in the decision-making process. (B)
- If performing prostate cancer screening, limit to men with greater than 10 years life expectancy. (B)
- Because the lead time of a diagnosis based on PSA screening is estimated to be 5 to 7 years, PSA screening every other year is unlikely to cause a loss of sensitivity. (B)
- Men with tumors with a Gleason score less than 5 are the best candidates for “watchful waiting,” having a favorable 20-year survival. (B)
Prostate cancer screening in asymptomatic men remains controversial, and it is difficult to present its benefits and risks quickly in a way that is understandable to patients. Yet many expert groups agree that physicians should enter into a mutual decision-making process with patients.1-3
This article reviews the latest information relevant to the controversy, offers “talking points” for family physicians to use when discussing screening with patients, and lists websites that patients may find helpful when making a decision about prostate cancer screening.
For this review, we searched for recent articles that are generalizable to a primary care population and of the highest evidence level available. We preferentially discuss population-based studies, studies from randomized trials of screening, and meta-analyses, rather than results that are hospital- or clinic-based. For a complete systematic review of this topic (from 2002), readers are referred to one conducted for the Agency for Healthcare Research and Quality.4 (See Scope of the problem).
Adenocarcinoma of the prostate is a significant public health burden. Age, family history, and race are the only known risk factors. Most cancers (86%) are diagnosed while still confined to the prostate; however, invasion beyond the capsule is sometimes not apparent until surgery.
Incidence. In 2005, there will be approximately 232,090 new cases of prostate cancer.5 American men have a 17% chance of being diagnosed with prostate cancer; African Americans have a 65% greater risk of developing prostate cancer than Caucasians.6 In fact, African Americans have the highest prostate cancer annual age-adjusted incidence rates in the world: 272/100,000 compared with 164/100,000 for Caucasian Americans.6 The rate for US Asian/Pacific Islander and Hispanic men is less than that for Caucasian Americans.
Mortality. There will be approximately 30,350 prostate cancer deaths in 2004.5 There is 3% chance of dying from prostate cancer; however, the risk of death is about 55% higher for African American men than Caucasian American men.6
Risk factors other than race. Risk of prostate cancer diagnosis increases with age: 1 in 48 men aged 40 to 59 years will be diagnosed with prostate cancer, while 1 in 8 men aged 60 to 79 years are at risk.7 A man who has a first-degree relative with prostate cancer is 2.4 times as likely to be diagnosed with prostate cancer as a man with no affected relatives.8
Key components of the controversy
How effective is screening?
A good screening test does 2 things. First, it detects a disease earlier than it would be detected with no screening at all, and it does so with sufficient accuracy to avoid a large number of false-positive and false-negative results.
Second, it leads to treatment of early disease that will likely produce a more favorable health outcome than waiting to treat patients who have signs and symptoms of disease.9 Unfortunately it is still unclear whether screening tests for prostate cancer meet these 2 criteria.
Skewed numbers. Yes, estimates of false-positive and false-negative results are available from numerous studies of different populations. However, in most studies, only men with abnormal test results receive a biopsy. Men with normal screening test results are not biopsied. Therefore the number of false negatives (and true negatives) is unknown. Furthermore, these estimates are often based on patients from urology clinics, a group more likely to have disease, thereby increasing the positive predictive value of a given screening test.
Whether current screening methods—in particular, prostate-specific antigen (PSA)—identify prostate cancers destined to become clinically relevant is also unknown. If screening does identify such cancers, a decrease in prostate cancer mortality among men who were screened is expected. If it does not, overdiagnosis and treatment of clinically insignificant cancers will negatively impact the quality of men’s lives without extending their life spans.
Clinical variability of the disease
The natural history of prostate cancer is uncertain. If cancer is left unidentified or untreated, more men will die with prostate cancer than of prostate cancer.