O0 SECTION 3 Preventive medicine and public Health Box 16-1 Screening Controversies: "Are you really saving Lives? And how much worry and lost quality of life Breast cancer and prostate cancer in particular illustrate the chal- the improvement in mortality in women between age 40 and 49 was lenge in weighing evidence of small changes in mortality against side small and that possible harms needed to be considered. Instead, ffects of screening and treatment. Because of the impact of screen- USPSTF recommended that physicians discuss the risks and benefits ing biases, only a change in overall mortality in the screened popula- eening with the women and to proceed according to the tion is considered evidence of an effective screening program. The benefit preferences. This change led to a significant media backlash debate about changes in the U.S. Preventive Services Task Force Many people claimed the decision amounted to"care rationing, and demonstrate that that the USPSTF had overstepped its mandate by weighing mortality few issues in preventive medicine have er to polarize the benefits against anxiety. The Task Force argued that the evidence and health care prof ort a"one size fits all" recommendation and that their guidelines empowered patients and their physicians to make rational Breast Cancer cisions based on evidence and more respectful of individual an io oe resp rematrurelities best cd ne. mnatormuonatemy, truly lead to a saved life; the majority are false-positive findings or lead = As of 2012, the rating is a"B" for women age 50 to 74( nded )and a"C for women 40 to 49, indicating that USPSTF the decision to screen should be individualized, and the net necessary diagnosis and treatment of lesions such as ductal carci is likely small. noma in situ(DCIS), which is not harmful to the majority of women Most women would not have known they had these DCIS lesions Prostate Cancer had it not been for the screening mammography. Women with DCIS re at increased risk for a subsequent diagnosis of invasive breast Prostate cancer affects men in a broad age range and has a wide cancer. Unfortunately, we cannot predict which women with DCIS whereas others are slow-growing and indolent. False-positive will ultimately go on to have invasive breast cancer. Thus, women results of prostate-specific antigen( PSA) testing are common ho are diagnosed with DCIS after a screenIng mammography often undergo breast surgery, chemotherapy, and radiation treatment that and often lead to other unnecessary invasive testing (e. g, biopsy can be costly and traumatic. Similarly, many women whose cancers This testing can then lead to diagnosis(often without a reliable way are detected by mammography still die of their disease. If mammo to distinguish between indolent and aggressive disease), treatment (e.g,surgery, radiation, and/or chemotherapy), and serious harm, mortality in populations screened should decrease. This hypothesis including erectile dysfunction, bladder and bowel incontinence, and death, to manage a disease that might otherwise have never been problematic(most men die with prostate cancer, not of prostate As of 2011, the strongest evidence shows that any difference in To date, the evidence that prostate verall mortality between populations exposed to screenings and cancer screening decreases all-cause or prostate cancer-specific those not screened is small: for every 2000 women invited for screen mortality. If there is any benefit, it likely accrues over more than 10 g throughout 10 years, one will have her life prolonged; 10 healthy years. Therefore, USPSTF advised in 2012 against routine screening omen who would not have been diagnosed if there had not will experience important psychological distress for many months Both these controversies illustrate the need of personalizing screen- because of false-positive findings tate cancer should be based on the patients risk preferences and In 2009, USPSTF changed its screening recommendations regarding willingness to have false-positive test results and invasive follow-up breast cancer for women age 40 to 49, Previously recommending testing. Many decision aids have been developed to help individua routine screening in this population, the Task Force now argued that make informed decisions They may delay medical visits that they might otherwise conducted. An RCT is needed to reduce the potential for have made promptly. False-negative results also may falsely bias In cancer an association between screening and longer reassure clinicians False-negative results can be detrimental survival does not prove a cause-and-effect relationship to the health of the people whose results were in error, and because of possible problems such as selection bias, lead test results delay the diagnosis in people who have an infec tious disease, such as tuberculosis, the screening tests can be Selection bias may affect a screening program in different dangerous to the health of others as well directions, all of which may make it difficult to generalize Overdiagnosis is another potential harm of scree ening findings to the general population. On one hand, individuals programs. For example, screening mammography may lead may want to participate because they have a family history to a diagnosis of a preinvasive lesion that is not invasive of the disease or are otherwise aware that they are at higher breast cancer(see Box 16-1). Actions taken in response to risk of contracting the disease. In this case the screening uch findings, including surgery, may result in a scenario program would find more cases than expected in the general where the ostensible " cure"is in fact worse than the disease. population, exaggerating the apparent utility of screening On the other hand. individuals who are more"health con- E. Bias in Screening Programs scious"may preferentially seek out screening program It is not easy to establish the value of a community screening Lead-time bias occurs when screen ling detects disease