asymptomatic person—is also a form of secondary prevention, and it is the focus of this chapter. Because primary prevention of skin cancer emphasizes actions to be taken by children and young adults, secondary prevention is the main issue for those over 65.

For people who already have a medical problem, usual clinical management may include measures to prevent additional problems or complications. These measures, sometimes described as tertiary prevention, include such steps as identification and elimination of oral infections before organ transplants and treatment with immunosuppressive drugs afterwards. Medicare coverage for diabetes outpatient self-management training and supplies, which was approved by Congress in 1997 as a preventive service, is another example of tertiary prevention.

The primary, secondary, and tertiary labels for preventive services are not rigidly applied. For example, much tertiary prevention is viewed as treatment and thus not subject to Medicare’s preventive services exclusion. The exclusion for outpatient drugs would, however, still apply to most of the medications used for tertiary prevention.

The premise underlying both self-examination and clinical screening programs is that detecting a disease earlier than would happen in usual health care will result in earlier treatment that saves lives and reduces the physical and emotional burden of illness. In addition, screening is often promoted as a way of reducing the overall costs associated with treating disease, especially late-stage disease. Nonetheless, when claims about the benefits of particular screening programs are subjected to systematic evaluation, the evidence supports some but is negative, mixed, limited, or otherwise inadequate to support others (see, e.g., Eddy, 1991; Russell, 1994; USPSTF, 1996).2 As controversies over assessments of breast cancer screening for women ages 40 to 49 demonstrate, conclusions that the evidence does not clearly support screening for a particular disease can generate considerable controversy, given the understandable hopes that screening will prevent or reduce the mortality, disability, and other suffering caused by the disease (see, e.g., Eddy, 1997; Ransohoff and Harris, 1997; Taubes, 1997a,b).

Medicare does not cover screening for skin cancer in asymptomatic people. It does, however, cover a physician visit initiated by a concerned patient who has noticed, for example, a change in the color of a mole (clinically described as a pigmented nevus or, more generally, skin lesion), or a new skin growth. Simi-


Claims about other prevention strategies become similarly complex when rigorously investigated. Proponents of evidence-based medicine will note that the results of the controlled trial of sunscreen use that was mentioned on the previous page supported—for squamous cell carcinoma—a prevention strategy that has long been promoted on the basis of biological plausibility without direct evidence (Hill, 1999). For basal cell carcinoma, the trial did not find a significant effect of sunscreen use. The trial also tested the use of beta-carotene supplements to prevent skin cancer. This strategy received some attention based on animal studies but was not confirmed in this trial.

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