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Health screening tests greatly impact the public's health because they involve testing of asymptomatic populations for specific diseases or health conditions for which specific interventions may alter disease progression before appearance of clinical signs and symptoms. The following criteria characterize an effective screening program:¹

• The screening test has acceptable performance specifications (positive and negative predictive values) for the disease in question
• The disease is a significant condition with major health and societal implications
• Acceptable, feasible and effective tests for presence of the disease and treatments are available
• Following screening, strategy to decide which patients to treat; those treated must be more likely to do better than those treated later when signs and symptoms appear in the absence of screening
• There must be a net benefit to the individual being screened for the disease while also considering the societal context
• The screening test is available, cost-effective and acceptable for the target population
• Informed consent and patient confidentiality must be ensured.

In this article, recommendations of the US Preventive Services Task Force (USPSTF) for selected laboratory-based screening tests are described. These screening tests include those for colorectal cancer, cardiovascular disease risk, hepatitis C virus (HCV) infection, human immunodeficiency virus (HIV) infection, syphilis infection, Type 2 diabetes mellitus, and prostate cancer. Additionally, specific CDC recommendations, are noted when applicable. 

The USPSTF, supported by the Agency for Healthcare Research and Quality, is widely considered to be the leading independent panel of experts in recommendations about disease prevention and in primary and secondary interventions. The USPSTF conducts rigorous and impartial assessments of the scientific evidence for effectiveness of a broad range of clinical preventive services. 

Evidence is evaluated using a rating scale: "A" (strong recommendation for screening), "B" (recommendation for screening), "C" (recommendation neither for nor against screening), "D" (recommendation against screening), or "I" (inadequate or insufficient evidence to recommend for or against screening). Table 1 lists the USPSTF screening recommendations for 19 diseases or conditions in adult men. Screening for six of these diseases or conditions received a rating of either A or B, while seven diseases or conditions received a rating of D. The USPSTF's recommendations for the six diseases or condition receiving a rating of either A or B will be discussed in more detail. Also discussed will be the recent USPSTF rating of D for screening of prostate cancer.

Colorectal Cancer: Screening for colorectal cancer using fecal occult blood testing (FOBT), sigmoidoscopy, or colonoscopy in adult men and women is strongly recommended beginning at age 50 years and continuing until 75 years of age (A).²  One of the following three screening methods may be used:

• Annual, high-sensitivity FOBT
• High-sensitivity FOBT every 3 years plus sigmoidoscopy every 5 years
• Screening colonoscopy every 10 years

The long preclinical phase from development of adenomas to colorectal carcinoma provides opportunities for successful screening, diagnosis, intervention, treatment, and extended lives.  However, routine screening in asymptomatic adults 75-85 years of age (B) and screening in asymptomatic adults older than 85 years of age with prior history of adequate screening is not recommended since there is at least moderate evidence that net benefit is small (C). There is adequate evidence that the benefits associated with detection and early intervention decline after age 75 years. The lead time between detection and treatment of colorectal cancer and a mortality benefit is substantial, but competing causes of mortality in this age group renders it less likely that this benefit will be realized with advancing age.

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