Screening for Prostate Cancer
Serum prostate-specific antigen (PSA) testing has become the method of choice for prostate cancer screening. However, PSA screening in asymptomatic men is under debate, because it can lead to overdetection and subsequent overtreatment of indolent disease.
Several recent studies showed differing results from prostate cancer screening.
The US Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial found that the mortality rate was no lower with combined PSA screening and digital rectal examination during a median follow-up of 11 years than in a control group that had a lower rate of screening. However, further analysis of these data, with stratifying by comorbidities, showed that PSA screening in young and healthy men reduces the risk of death from prostate cancer, with minimal overtreatment.
The European Randomized Study of Screening for Prostate Cancer found a statistically significant 20% reduction in deaths from prostate cancer with PSA screening, but that it was necessary to treat 48 men in order to save one life. Another study, published in 2010, showed that regular PSA screening reduced the rate of prostate cancer mortality by half over 14 years.
African American men generally present with disease that is more advanced than in white men. This historically has been attributed to the fact that African Americans have been less likely to be screened for prostate cancer, though recent data indicate the gap is lessening. A cross-sectional study from the Texas Medical Center showed that 54.4% of African American men had received PSA screening, compared with 63.2% of white men.
Another study showed that African Americans were more likely to have had a longer interval between PSA screenings before diagnosis, and that a longer PSA screening interval was associated with greater odds of having advanced disease at diagnosis. However, when the researchers controlled for the PSA screening interval, they found that African Americans had the same odds of being diagnosed with advanced prostate cancer as white patients did. They concluded that more frequent or systematic PSA screening may reduce the racial differences in cancer stage at diagnosis and in deaths.
Reasons for the disparities in screening
Many reasons have been proposed to explain why African Americans receive less screening, including poor communication between physicians and minority patients due to lack of cultural competency among physicians, lack of health insurance (and poor access to quality care as a result), and deficiency of knowledge about screening. Though awareness is rising, many African Americans are unaware of early detection methods for prostate cancer (eg, PSA testing), and other barriers such as cost and transportation exist that may prevent African American men from being screened. As gatekeepers, primary care physicians are in a position to address these shortcomings in patient education and to enhance the physician-patient relationship.
Black men have higher PSA levels, with or without cancer
Physicians must also be aware of racial differences in PSA levels and realize that the predictive value of PSA in the diagnosis of prostate cancer may differ between African Americans and whites.
Black men, with or without prostate cancer, have been found to have higher PSA levels. Kyle and colleagues found that African American men without prostate cancer had significantly higher mean PSA levels than white men across all age groups. Furthermore, Vijayakumar et al found that African Americans with newly diagnosed localized prostate cancer had higher serum PSA levels than whites at diagnosis.
Although PSA cutoff levels have not been officially modified according to race, primary care physicians should have a lower threshold for referring African American men who have a suspiciously high PSA level for further urologic evaluation. Close partnership between the internist, family practitioner, and urologist will aid in the optimal use of PSA testing for the early detection of prostate cancer.
When to start PSA screening? How often to screen?
The age at which African American men should begin to have their PSA levels checked (with or without a digital rectal examination) continues to debated. However, the American Cancer Society recommends that African American men who have a father or brother who had prostate cancer before age 65 should begin having discussions with their physician on this topic and, with their informed consent, screening at age 45.
The frequency of PSA screening depends on the individual’s PSA level. The National Comprehensive Cancer Network recommends that men at high risk be offered a baseline PSA measurement and digital rectal examination at age 40 and, if the PSA level is higher than 1 ng/mL, that they be offered annual follow-ups. If the PSA level is less than 1 ng/mL, they recommend screening again at age 45. Risk factors for prostate cancer include family history as well as African American race.
Part (3/4) will be uploaded soon.
For additional information or inquiries, visit the link below to view the original published article by Dr. Charles Modlin and Dr. Ina Wu: http://www.ccjm.org/content/79/5/313.full