The two main screening modalities for prostate cancer include digital rectal examination (DRE) and serum prostate-specific antigen (PSA; concentration more than 4ng/dl) and endorectal (transrectal) ultrasonography (TRUS). The most widely used and oldest technique for detection of prostate cancer is the DRE ranges in estimates of sensitivity and specificity are reported, Estimates suggest a PPV of 15% to 30% and sensitivity of approximately 60%. Ultimately, only one in three patients with a positive DRE has prostate cancer. With the development and application of intraluminal (rectal) probes with high resolution, studies have shown that small, nonpalpable malignant lesions of the prostate could be detected. TRUS has fallen short of expectations, with large variation in reports of sensitivity and specificity, both ranging from 41% to 79%. Despite this, TRUS is considered an excellent ancillary modality to increase accuracy of biopsy over the digital guidance alone.
PSA is a blood test that allows for earlier detection of many prostate cancers, with sensitivity of up to 80% to 85%. Unfortunately, PSA tests have low specificity, resulting in high rates of false-positives. Interest in the PSA grew in the late 1980s as PSA levels were shouwn to drop to undetectable levels after prostatectomy. However, normal PSA values are found in approximately one-third of men with localized cancers, and PSA levels are often elevated in men with noncancerous conditions, such as benign prostatic hyperplasia. Only approximately 7% of prostate cancers detected by screening are microfocal and low grade.
Some investigators have argued that integration of DRE with determination of PSA levels and the use of TRUS in selected cases should improve prostate cancer detection. Using age-specific PSA ranges may be a promising strategy for increasing PSA sensitivity. Prostate cancer screening is more controversial in older men; concerns about quality of life outweigh potential benefit of screening. Several reports indicate that men over age 70 years are unlikely to benefit from PSA testing.
Nonrandomized Studies
Two nonrandomized studies are ongoing to evaluate screening tests for prostate cancer [the ACS National Prostate Cancer Detection Project (ACS-NPCDP) and a multi-center study headquartered at Washington University involving 6 university medical centers]. Results of the ACS-NPCDP trial indicate that a combined modality approach (DRE, TRUS and PSA) to prostate cancer detection yields high levels of early detection. Data from the Washington University study also indicate that screening with PSA or PSA in combination with DRE, or both, is reasonable for detecting carcinomas at an early stage. Continued follow-up to evaluate longer-term morbidity and mortality data from these studies will not be available until the end of the first decade of the twenty-first century. Thus, clinicians and patients must make decisions in the absence of RCT data.
PSA is a blood test that allows for earlier detection of many prostate cancers, with sensitivity of up to 80% to 85%. Unfortunately, PSA tests have low specificity, resulting in high rates of false-positives. Interest in the PSA grew in the late 1980s as PSA levels were shouwn to drop to undetectable levels after prostatectomy. However, normal PSA values are found in approximately one-third of men with localized cancers, and PSA levels are often elevated in men with noncancerous conditions, such as benign prostatic hyperplasia. Only approximately 7% of prostate cancers detected by screening are microfocal and low grade.
Some investigators have argued that integration of DRE with determination of PSA levels and the use of TRUS in selected cases should improve prostate cancer detection. Using age-specific PSA ranges may be a promising strategy for increasing PSA sensitivity. Prostate cancer screening is more controversial in older men; concerns about quality of life outweigh potential benefit of screening. Several reports indicate that men over age 70 years are unlikely to benefit from PSA testing.
Nonrandomized Studies
Two nonrandomized studies are ongoing to evaluate screening tests for prostate cancer [the ACS National Prostate Cancer Detection Project (ACS-NPCDP) and a multi-center study headquartered at Washington University involving 6 university medical centers]. Results of the ACS-NPCDP trial indicate that a combined modality approach (DRE, TRUS and PSA) to prostate cancer detection yields high levels of early detection. Data from the Washington University study also indicate that screening with PSA or PSA in combination with DRE, or both, is reasonable for detecting carcinomas at an early stage. Continued follow-up to evaluate longer-term morbidity and mortality data from these studies will not be available until the end of the first decade of the twenty-first century. Thus, clinicians and patients must make decisions in the absence of RCT data.
