Agency for Healthcare Research and Quality.

Early detection of cancer has held great promise and intuitive appeal in the medical community for well over a century. Its history developed in tandem with that of the periodic health examination, in which any deviations-subtle or glaring--from a clearly demarcated "normal" were to be rooted out, given the underlying hypothesis that diseases develop along progressive linear paths of increasing abnormalities. This model of disease development drove the logical deduction that early detection-by "breaking the chain" of cancer development--must be of benefit to affected individuals. In the latter half of the 20 th century, researchers and guidelines organizations began to explicitly challenge the core assumptions underpinning many clinical practices. A move away from intuitive thinking began with the development of evidence-based medicine. One key method developed to explicitly quantify the overall risk-benefit profile of a given procedure was the analytic framework. The shift away from pure deductive reasoning and reliance on personal observation was driven, in part, by a rising awareness of critical biases in cancer screening that can mislead clinicians, including healthy volunteer bias, length-biased sampling, lead-time bias, and overdiagnosis. A new focus on the net balance of both benefits and harms when determining the overall worth of an intervention also arose: it was recognized that the potential downsides of early detection were frequently overlooked or discounted because screening is performed on basically healthy persons and initially involves relatively noninvasive methods. Although still inconsistently applied to early detection programs, policies, and belief systems in the United States, an evidencebased approach is essential to counteract the misleading-even potentially harmful--allure of intuition and individual observation.

National Cancer Institute.

PURPOSE Multiple cancer screening tests have been advocated for the general population; however, clinicians and patients are not always well-informed of screening burdens. We sought to determine the cumulative risk of a false-positive screening result and the resulting risk of a diagnostic procedure for an individual participating in a multimodal cancer screening program.METHODS Data were analyzed from the intervention arm of the ongoing Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a randomized controlled trial to determine the effects of prostate, lung, colorectal, and ovarian cancer screening on disease-specifi c mortality. The 68,436 participants, aged 55 to 74 years, were randomized to screening or usual care. Women received serial serum tests to detect cancer antigen 125 (CA-125), transvaginal sonograms, posteroanterior-view chest radiographs, and fl exible sigmoidoscopies. Men received serial chest radiographs, fl exible sigmoidoscopies, digital rectal examinations, and serum prostate-specifi c antigen tests. Fourteen screening examinations for each sex were possible during the 3-year screening period.RESULTS After 14 tests, the cumulative risk of having at least 1 false-positive screening test is 60.4% (95% CI, 59.8%-61.0%) for men, and 48.8% (95% CI, 48.1%-49.4%) for women. The cumulative risk after 14 tests of undergoing an invasive diagnostic procedure prompted by a false-positive test is 28.5% (CI, 27.8%-29.3%) for men and 22.1% (95% CI, 21.4%-22.7%) for women. CONCLUSIONSFor an individual in a multimodal cancer screening trial, the risk of a false-positive fi nding is about 50% or greater by the 14th test. Physicians should educate patients about the likelihood of false positives and resulting diagnostic interventions when counseling about cancer scree ning. Ann Fam Med 2009;7:212-222. DOI: 10.1370/afm.942. INTRODUCTIONN umerous cancer screening tests are promoted to the healthy public. [1][2][3][4][5][6][7][8] The motivating factor behind regular cancer screening is the theory that the earlier one detects a malignancy or premalignancy, the more likely treatment is to be effective in increasing lifespan while minimizing harms caused by the therapy. 9 Although this model has intuitive appeal, it is often used without actual proof in hand and without full consideration of potential adverse consequences. The most common potential adverse consequence is a false-positive result, which often brings with it physical, psychological, and economic burdens of further diagnostic testing. [10][11][12][13] The false-positive rate of a single screening test has been studied, but the cumulative false-positive rate of repeating the test at regular intervals is infrequently reported, [14][15][16][17] and the cumulative false-positive rate of multiple tests has not, to our knowledge, been reported at all. The ongoing Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial is designed to assess the benefi ts and harms of screening for 4 major causes of cancer mortality. As...

BackgroundPreterm birth is a global health priority. Using a progestogen during high-risk pregnancy could reduce PTB and adverse neonatal outcomes. MethodsSystematic review of randomised trials comparing vaginal progesterone, intramuscular 17hydroxyprogesterone caproate (17-OHPC), or oral progesterone with control, or with each other, in asymptomatic women at risk of preterm birth. We identified published and unpublished trials that completed primary data collection before July 30, 2016 (12 months before data collection began) by searching MEDLINE, Embase, CINAHL, the Maternity and Infant Care Database, and relevant trial registers between inception and July 30, 2019. Trials of progestogen to prevent early miscarriage or immediately-threatened preterm birth were excluded. Individual participant data were requested from investigators of eligible trials. Outcomes included preterm birth, early preterm birth, and mid-trimester birth. Adverse neonatal sequelae associated with early births were assessed using a composite of serious neonatal complications, and individually. Adverse maternal outcomes were investigated as a composite and individually. Individual participant data were checked and risk of bias assessed independently by two researchers. Primary meta-analyses used one-stage generalised linear mixed models that incorporated random effects to allow for heterogeneity across trials. FindingsInitial searches identified 47 eligible trials. Individual participant data were available for 30 of these trials. An additional trial was later included in a targeted update. Data were therefore available from a total of 31 trials (11,644 women and 16,185 offspring). Trials in singleton pregnancies included mostly women with previous spontaneous preterm birth or short cervix. Preterm birth before 34 weeks was reduced in such women who received vaginal progesterone (nine trials, 769 women; relative risk [RR] 0•78, 95% CI 0•68-0•90), 17-OHPC (five trials, 3,053 women; 0•83, 0•68-1•01), and oral progesterone (two trials, 183 women; 0•60, 0•41-0•90). Results for other birth and neonatal outcomes were consistently favourable, but less certain. A possible increase in maternal complications was suggested, but this was uncertain. We identified no consistent evidence of treatment interaction with any participant characteristics examined, although analyses within subpopulations questioned efficacy in women who did not have a short cervix. Trials in multifetal pregnancies mostly included women without additional risk factors. For twins, vaginal progesterone did not reduce preterm birth before 34 weeks (eight trials, 2046 women: RR 1•01, 95% CI 0•84-1•20) nor did 17-OHPC for twins or triplets (eight trials, 2253 women: 1•04, 0•92-1•18). Preterm premature rupture of membranes was increased with 17-OHPC exposure in multifetal gestations (rupture <34 weeks RR 1•59, 95% CI 1•15-2•22), but we found no consistent evidence of benefit or harm for other outcomes with either vaginal progesterone or 17-OHPC InterpretationVaginal progesterone and 17...