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Background: Cancer prevention and screening guidelines are ideally suited to the task of providing high-quality benefit-harm information that informs clinical practice. We systematically examined how US guidelines present benefits and harms for recommended cancer prevention and screening interventions., Methods: We included cancer screening and prevention recommendations from: 1) the United States Preventive Services Task Force, 2) the American Cancer Society, 3) the American College of Physicians, 4) the National Comprehensive Cancer Network, and 5) other US guidelines within the National Guidelines Clearinghouse. Searches took place November 20, 2013, and January 1, 2014, and updates were reviewed through July 1, 2015. Two coders used an abstraction form to code information about benefits and harms presented anywhere within a guideline document, including appendices. The primary outcome was each recommendation's benefit-harm "comparability" rating, based on how benefits and harms were presented. Recommendations presenting absolute effects for both benefits and harms received a "comparable" rating. Other recommendations received an incomplete rating or an asymmetric rating based on prespecified criteria., Results: Fifty-five recommendations for using interventions to prevent or detect breast, prostate, colon, cervical, and lung cancer were identified among 32 guidelines. Thirty point nine percent (n = 17) received a comparable rating, 14.5% (n = 8) received an incomplete rating, and 54.5% (n = 30) received an asymmetric rating., Conclusions: Sixty-nine percent of cancer prevention and screening recommendation statements either did not quantify benefits and harms or presented them in an asymmetric manner. Improved presentation of benefits and harms in guidelines would better ensure that clinicians and patients have access to the information required for making informed decisions., (Published by Oxford University Press 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

It is impossible to predict exactly who will develop a cancer and who will not. We know that several "risk factors" may increase the chance of getting cancer and that risk increases with age. However, even with that in mind we seem to be able to explain only a certain number of cancers. Recently, Tomasetti and Vogelstein published a provocative article in Science stating that a large percentage of cancers may be due to "bad luck" (stochastic mutation events during DNA replication) and only a few to carcinogens, pathogens, or inherited genes and that this should impact public health policies. However, their intriguing analysis has numerous limitations, some of which have already been commented upon, including the likely biased subset of cancers and that finding a correlation does not signify a cause-effect mechanism. Here, we point out that there may also be an alternative explanation for the data, the cancer stem cell hypothesis, which postulates that cancers are derived from tissue stem cells and not from somatic differentiated cells. We also highlight the importance of the tissue microenvironment in the growth of transformed cells and outline a table of concurrent factors for several cancers. The message communicated to the public should not be one of helplessness in avoiding cancers, particularly given the now extensive knowledge of known risk factors and several agents/behaviors that can lower risk for specific cancers. While some tumors will still be due to chance, prevention should still be a primary goal for public health policies., (© The Author 2015. Published by Oxford University Press.)

Background: The aim of this study was to quantify the benefits and harms of mammography screening after age 74 years, focusing on the amount of overdiagnosis of invasive breast cancer and ductal carcinoma in situ (DCIS)., Methods: Three well-established microsimulation models were used to simulate a cohort of American women born in 1960. All women received biennial screening starting at age 50 years with cessation ages varying from 74 up to 96 years. We estimated the number of life-years gained (LYG), quality-adjusted life-years, breast cancer deaths averted, false-positives, and overdiagnosed women per 1000 screens., Results: The models predicted that there were 7.8 to 11.4 LYG per 1000 screens at age 74 years (range across models), decreasing to 4.8 to 7.8 LYG per 1000 screens at age 80 years, and 1.4 to 2.4 LYG per 1000 screens at age 90 years. When adjusted for quality-of-life decrements, the LYG decreased by 5% to 13% at age 74 years and 11% to 22% at age 80 years. At age 90 to 92 years, all LYG were counterbalanced by a loss in quality-of-life, mainly because of the increasing number of overdiagnosed breast cancers per 1000 screens: 1.2 to 5.0 at age 74 years, 1.8 to 6.0 at age 80 years, and 3.7 to 7.5 at age 90 years. The age at which harms began to outweigh benefits shifted to a younger age when larger or longer utility losses because of a breast cancer diagnosis were assumed., Conclusion: The balance between screening benefits and harms becomes less favorable after age 74 years. At age 90 years, harms outweigh benefits, largely as a consequence of overdiagnosis. This age was the same across the three models, despite important model differences in assumptions on DCIS., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The aim of cancer screening is to detect asymptomatic cancers whose treatment will result in extension of life, relative to length of life absent screening. Unfortunately, cancer screening also results in overdiagnosis, the detection of cancers that, in the absence of screening, would not present symptomatically during one's lifetime. Thus, their detection and subsequent treatment is unnecessary and detrimental. This definition of overdiagnosis, while succinct, does not capture the ways it can occur, and our interactions with patients, advocates, researchers, clinicians, and journalists have led us to believe that the concept of overdiagnosis is difficult to explain and, for some, difficult to accept. We propose a dichotomy, the "tumor-patient" classification, to aid in understanding overdiagnosis. The tumor category includes asymptomatic malignant disease that would regress spontaneously if left alone, as well as asymptomatic malignant disease that stagnates or progresses too slowly to be life threatening in even the longest of lifetimes. The patient category includes asymptomatic malignant disease that would progress quickly enough to be life threatening during a lifetime of typical length, but lacks clinical relevance because death due to another cause intercedes prior to what would have been the date of symptomatic diagnosis had screening not occurred. Cancer screening of most organs is likely to result in overdiagnosis of both types. However, the ratio of tumor- to patient-driven overdiagnosis almost certainly varies, and may vary drastically, by organ, screening modality, patient characteristics, and other factors., (© Published by Oxford University Press 2015.)

The frequency of overdiagnosis associated with breast cancer screening is a topic of controversy. Published estimates vary widely, but identifying which estimates are reliable is challenging. In this article we present an approach that provides a check on these estimates. Our approach leverages the close link between overdiagnosis and lead time by identifying the average lead time most consistent with a given overdiagnosis frequency. We consider a high-profile study that suggested that 31% of breast cancers diagnosed in the United States in 2008 were overdiagnosed and show that this corresponds to an average lead time of about nine years among localized cases. Comparing this estimate with the average lead time for invasive, screen-detected breast cancers of 40 months, around which there is a relative consensus, suggests the published estimate of overdiagnosis is excessive. This approach provides a novel way to appraise estimates of overdiagnosis given knowledge of disease natural history., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Background: Compared with film, digital mammography has superior sensitivity but lower specificity for women aged 40 to 49 years and women with dense breasts. Digital has replaced film in virtually all US facilities, but overall population health and cost from use of this technology are unclear., Methods: Using five independent models, we compared digital screening strategies starting at age 40 or 50 years applied annually, biennially, or based on density with biennial film screening from ages 50 to 74 years and with no screening. Common data elements included cancer incidence and test performance, both modified by breast density. Lifetime outcomes included mortality, quality-adjusted life-years, and screening and treatment costs., Results: For every 1000 women screened biennially from age 50 to 74 years, switching to digital from film yielded a median within-model improvement of 2 life-years, 0.27 additional deaths averted, 220 additional false-positive results, and $0.35 million more in costs. For an individual woman, this translates to a health gain of 0.73 days. Extending biennial digital screening to women ages 40 to 49 years was cost-effective, although results were sensitive to quality-of-life decrements related to screening and false positives. Targeting annual screening by density yielded similar outcomes to targeting by age. Annual screening approaches could increase costs to $5.26 million per 1000 women, in part because of higher numbers of screens and false positives, and were not efficient or cost-effective., Conclusions: The transition to digital breast cancer screening in the United States increased total costs for small added health benefits. The value of digital mammography screening among women aged 40 to 49 years depends on women's preferences regarding false positives., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Over the last few decades there has been an increase in the use of strategies to detect clinically occult breast cancer with the aim of achieving diagnosis at an earlier stage when prognosis may be improved. Such strategies include screening mammography in healthy women, diagnostic imaging and axillary staging in those diagnosed with breast cancer, and the use of follow-up imaging for the early detection of recurrent or metastatic disease. Some of these strategies are established, whereas for others there are inconsistent supportive data. Although the potential benefit of early detection of clinically occult breast cancer seems intuitive, use of such strategies can also be associated with harm. In this commentary, we provide an extended discussion on the potential benefits and harms of the routine and frequent use of screening interventions to detect clinically occult breast cancer and question whether we may be causing more harm than good.

It has been more than 30 years since the first consensus development meeting was held to deal with guidelines of mammography screening. Although the National Cancer Institute has wisely focused on the science of screening and of screening benefits vs harm, many professional organizations, advocacy groups, and the media have maintained a focus on establishing who should be screened and promoting recommendations for which age groups should be screened. Guidelines have been developed not only for mammography but also for screening at virtually all major cancer sites, especially for prostate cancer, and most recently, with the preliminary results of the National Lung Screening Trial, for lung cancer. It seems clear that we have done an inadequate job of educating screening candidates about the harms and benefits of cancer screening, including the extent to which screening can reduce cancer mortality. We must also question whether our practice of summoning women to have mammograms, while providing men informed choice for prostate cancer screening, is consistent with a scientific analysis of the relative harms and benefits. We have spent a staggering amount of time and energy over the past several decades developing, discussing, and debating guidelines. Professional and advocacy groups have spent much time aggressively advocating the adoption of guidelines supported by their respective groups. It seems that it would be much more productive to devote such energy to educating screening candidates about the harms and benefits of screening and to engaging in shared decision making.

Despite mortality reductions found in early trials, recent population-based data suggest that breast and prostate cancer screening have not yielded expected benefits. Whereas evidence-based appraisals generally mistrust disease-specific mortality as a primary outcome measure, cancer screening trials have consistently used this endpoint, largely because of the impracticality of studies with enough statistical power to detect all-cause mortality reductions, which would require millions of subjects. The acceptance of disease-specific mortality as a practical surrogate for all-cause mortality may explain the discrepancy between expected and actual impact. Screening may reduce deaths from the target cancer but may increase deaths from other causes, most likely because of overdiagnosis, an increasingly recognized risk of cancer screening. Recognition of the discrepancy between the expected and the actual impact of screening and recognition of overdiagnosis as a source of harm may be critical for understanding and projecting the potential impact of cancer screening programs.

Background: Although there is uncertainty about the effect of prostate-specific antigen (PSA) screening on the rate of prostate cancer death, there is little uncertainty about its effect on the rate of prostate cancer diagnosis. Systematic estimates of the number of men affected, however, to our knowledge, do not exist., Methods: We obtained data on age-specific incidence and initial course of therapy from the National Cancer Institute's Surveillance, Epidemiology, and End Results program. We then used age-specific male population estimates from the US Census to determine the excess (or deficit) in the number of men diagnosed and treated in each year after 1986-the year before PSA screening was introduced., Results: Overall incidence of prostate cancer rose rapidly after 1986, peaked in 1992, and then declined, albeit to levels considerably higher than those in 1986. Overall incidence, however, obscured distinct age-specific patterns: The relative incidence rate (2005 relative to 1986) was 0.56 in men aged 80 years and older, 1.09 in men aged 70-79 years, 1.91 in men aged 60-69 years, 3.64 in men aged 50-59 years, and 7.23 in men younger than 50 years. Since 1986, an estimated additional 1 305 600 men were diagnosed with prostate cancer, 1 004 800 of whom were definitively treated for the disease. Using the most optimistic assumption about the benefit of screening-that the entire decline in prostate cancer mortality observed during this period is attributable to this additional diagnosis-we estimated that, for each man who experienced the presumed benefit, more than 20 had to be diagnosed with prostate cancer., Conclusions: The introduction of PSA screening has resulted in more than 1 million additional men being diagnosed and treated for prostate cancer in the United States. The growth is particularly dramatic for younger men. Given the considerable time that has passed since PSA screening began, most of this excess incidence must represent overdiagnosis.

Background: The time by which prostate-specific antigen (PSA) screening advances prostate cancer diagnosis, called the lead time, has been reported by several studies, but results have varied widely, with mean lead times ranging from 3 to 12 years. A quantity that is closely linked with the lead time is the overdiagnosis frequency, which is the fraction of screen-detected cancers that would not have been diagnosed in the absence of screening. Reported overdiagnosis estimates have also been variable, ranging from 25% to greater than 80% of screen-detected cancers., Methods: We used three independently developed mathematical models of prostate cancer progression and detection that were calibrated to incidence data from the Surveillance, Epidemiology, and End Results program to estimate lead times and the fraction of overdiagnosed cancers due to PSA screening among US men aged 54-80 years in 1985-2000. Lead times were estimated by use of three definitions. We also compared US and earlier estimates from the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer (ERSPC) that were calculated by use of a microsimulation screening analysis (MISCAN) model., Results: The models yielded similar estimates for each definition of lead time, but estimates differed across definitions. Among screen-detected cancers that would have been diagnosed in the patients' lifetimes, the estimated mean lead time ranged from 5.4 to 6.9 years across models, and overdiagnosis ranged from 23% to 42% of all screen-detected cancers. The original MISCAN model fitted to ERSPC Rotterdam data predicted a mean lead time of 7.9 years and an overdiagnosis estimate of 66%; in the model that was calibrated to the US data, these were 6.9 years and 42%, respectively., Conclusion: The precise definition and the population used to estimate lead time and overdiagnosis can be important drivers of study results and should be clearly specified.

BRCA mutation carriers are recommended to start mammographic screening for breast cancer as early as age 25-30 years. We used an excess relative risk model (based on a pooled analysis of three cohorts with 7600 subjects who received radiation exposure) to estimate the lifetime risk of radiation-induced breast cancer from five annual mammographic screenings in young (<40 years) BRCA mutation carriers. We then estimated the reduction in breast cancer mortality required to outweigh the radiation risk. Breast cancer rates for mutation carriers were based on a pooled analysis of 22 pedigree studies with 8139 subjects. For BRCA1 mutation carriers, the estimated lifetime risk of radiation-induced breast cancer mortality per 10,000 women resulting from annual mammography was 26 (95% confidence interval [CI] = 14 to 49) for screening at age 25-29 years, 20 (95% CI = 11 to 39) for screening at age 30-34 years, and 13 (95% CI = 7 to 23) for screening at age 35-39 years. To outweigh these risks, screening would have to reduce breast cancer mortality by 51% (95% CI = 27% to 96%) at age 25-29 years, by 12% (95% CI = 6% to 23%) at age 30-34 years, and by 4% (95% CI = 2% to 7%) at age 35-39 years; estimates were similar for BRCA2 mutation carriers. If we assume that the mortality reduction from mammography is 15%-25% or less for young women, these results suggest that there would be no net benefit from annual mammographic screening of BRCA mutation carriers at age 25-29 years; the net benefit would be zero or small at age 30-34 years, but there should be some net benefit at age 35 or older. These results depend on a number of assumptions due to the absence of empiric data. The impact of varying these assumptions was therefore examined.

Background: Many guidelines recommend screening mammography every 1-2 years for women older than 40 years; more than 70% of women now participate in routine screening. No studies have examined the societal impact of screening practices over the past decade in the United States on costs and quality-adjusted life-years (QALYs). We performed a retrospective cost-effectiveness analysis comparing actual and alternative screening mammography scenarios., Methods: We used a discrete-event simulation model of breast cancer epidemiology to estimate the costs and the number of QALYs that were associated with observed screening mammography patterns in the United States from 1990 to 2000 for women aged 40 years or older. We also estimated costs and QALYS for no screening and for 64 alternative screening scenarios. Incremental cost-effectiveness ratios were computed. Sensitivity analyses were performed on key parameters., Results: Actual U.S. screening patterns from 1990 to 2000 accrued 947.5 million QALYs and cost $166 billion over the lifetimes of the screened women, resulting in a gain of 1.7 million QALYs for an additional cost of $62.5 billion compared with no screening. Among those polices that were not dominated--i.e., for which no alternative existed that produced more QALYs for lower costs--screening all women aged 40-80 years annually per some U.S. guidelines was the most expensive option, costing $58,000 per additional QALY gained compared with the next most costly alternative, screening all women aged 45-80 years annually. Many alternative screening scenarios generated more QALYs for less cost (with savings up to $6 billion) than actual screening patterns over the study period. Sensitivity analysis showed that conclusions about the cost-effectiveness of screening mammography policies were highly sensitive to small, short-term detrimental effects on quality of life from the screening test itself., Conclusions: Choosing among the efficient policies to guide current screening recommendations requires consideration of costs to promote participation in screening and measurement of acute quality-of-life effects of mammography.

Background: Well-designed evaluations of health services are frequently made today. However, the extent of the evaluations' benefits and costs is not well documented, creating uncertainty whether their use is optimal from society's perspective. We examined these costs and benefits using data from one well-designed evaluation, the Quebec Neuroblastoma Screening Project (QNSP). It screened most Quebec newborns between 1989 and 1994 for neuroblastoma. As previously reported, the screening did not reduce neuroblastoma mortality and caused adverse health effects., Methods: We compared the cost of doing the QNSP with its benefits. Had the QNSP not been undertaken, neuroblastoma screening would have been implemented throughout North America. We assume that screening would have started in 1989 and ended in 2002. The QNSP's benefits include the health costs and adverse health effects averted by not using ineffective screening during those 14 years. In our calculations we used neuroblastoma incidence data for the QNSP and for Ontario where there was no screening, detailed data describing the health services used by the patients, and Quebec cost data for those services., Results: The QNSP cost 8.77 million dollars (2002 US dollars). By not implementing similar screening programs between 1989 and 2002, the United States and Canada avoided 574.1 million dollars in health costs, the unnecessary treatment of 9223 children, and false-positive findings for 5003 children screened., Conclusions: The health care costs and adverse health effects averted by the QNSP justify its costs. These results show that well-designed evaluations can yield--at least sometimes--benefits substantially greater than their high costs. This raises an important policy issue: are these evaluations now being under- or over used?

Background: Screening for prostate cancer advances the time of diagnosis (lead time) and detects cancers that would not have been diagnosed in the absence of screening (overdetection). Both consequences have considerable impact on the net benefits of screening., Methods: We developed simulation models based on results of the Rotterdam section of the European Randomized Study of Screening for Prostate Cancer (ERSPC), which enrolled 42,376 men and in which 1498 cases of prostate cancer were identified, and on baseline prostate cancer incidence and stage distribution data. The models were used to predict mean lead times, overdetection rates, and ranges (corresponding to approximate 95% confidence intervals) associated with different screening programs., Results: Mean lead times and rates of overdetection depended on a man's age at screening. For a single screening test at age 55, the estimated mean lead time was 12.3 years (range = 11.6-14.1 years) and the overdetection rate was 27% (range = 24%-37%); at age 75, the estimates were 6.0 years (range = 5.8-6.3 years) and 56% (range = 53%-61%), respectively. For a screening program with a 4-year screening interval from age 55 to 67, the estimated mean lead time was 11.2 years (range = 10.8-12.1 years), and the overdetection rate was 48% (range = 44%-55%). This screening program raised the lifetime risk of a prostate cancer diagnosis from 6.4% to 10.6%, a relative increase of 65% (range = 56%-87%). In annual screening from age 55 to 67, the estimated overdetection rate was 50% (range = 46%-57%) and the lifetime prostate cancer risk was increased by 80% (range = 69%-116%). Extending annual or quadrennial screening to the age of 75 would result in at least two cases of overdetection for every clinically relevant cancer detected., Conclusions: These model-based lead-time estimates support a prostate cancer screening interval of more than 1 year.

Background: The cumulative risk of a false-positive mammogram can be substantial. We studied which variables affect the chance of a false-positive mammogram and estimated cumulative risks over nine sequential mammograms., Methods: We used medical records of 2227 randomly selected women who were 40-69 years of age on July 1, 1983, and had at least one screening mammogram. We used a Bayesian discrete hazard regression model developed for this study to test the effect of patient and radiologic variables on a first false-positive screening and to calculate cumulative risks of a false-positive mammogram., Results: Of 9747 screening mammograms, 6. 5% were false-positive; 23.8% of women experienced at least one false-positive result. After nine mammograms, the risk of a false-positive mammogram was 43.1% (95% confidence interval [CI] = 36.6%-53.6%). Risk ratios decreased with increasing age and increased with number of breast biopsies, family history of breast cancer, estrogen use, time between screenings, no comparison with previous mammograms, and the radiologist's tendency to call mammograms abnormal. For a woman with highest-risk variables, the estimated risk for a false-positive mammogram at the first and by the ninth mammogram was 98.1% (95% CI = 69.3%-100%) and 100% (95% CI = 99.9%-100%), respectively. A woman with lowest-risk variables had estimated risks of 0.7% (95% CI = 0.2%-1.9%) and 4.6% (95% CI = 1. 1%-12.5%), respectively., Conclusions: The cumulative risk of a false-positive mammogram over time varies substantially, depending on a woman's own risk profile and on several factors related to radiologic screening. By the ninth mammogram, the risk can be as low as 5% for women with low-risk variables and as high as 100% for women with multiple high-risk factors.

Background: Population-based screening for prostate cancer is currently being evaluated in randomized clinical trials in the United States and in Europe. Side effects arising from the process of screening and from the earlier treatment of screen-detected prostate cancer may be important factors in the evaluation. To examine health-related quality of life (or health status) among men screened for prostate cancer, we conducted a longitudinal study of 626 attenders to the Rotterdam (The Netherlands) prostate cancer screening program and of 500 nonparticipants., Methods: Attenders of the screening program and nonparticipants completed self-assessment questionnaires (SF-36 [i.e., Medical Outcomes Study 36-Item Short-Form Health Survey] and EQ-5D [i.e., EuroQol measure for health-related quality of life] health surveys) to measure generic health status, as well as an additional questionnaire for anxiety and items relating to prostate cancer screening., Results: Physical discomfort during digital rectal examination and during transrectal ultrasound was reported by 181 (37%) of 491 men and by 139 (29%) of 487 men, respectively; discomfort during prostate biopsy was reported by 64 (55%) of 116 men. Mean scores for health status and anxiety indicated that the participants did not experience relevant changes in physical, psychological, and social functioning during the screening procedure. However, high levels of anxiety were observed throughout the screening process among men with a high predisposition to anxiety. Similar scores for anxiety predisposition were observed among attenders and nonparticipants., Conclusions: At the group level, we did not find evidence that prostate cancer screening induced important short-term health-status effects, despite the short-lasting side effects related to the biopsy procedure. However, subgroups may experience high levels of anxiety. The implication is that unfavorable health-status effects of prostate cancer screening occur mainly in the treatment phase.

Background: Psychological distress following false-positive results could constitute a substantial disadvantage of cancer screening., Purpose: The purpose of this prospective study was to evaluate the psychological impact of true-negative and false-positive results in a high-risk group of women in a screening program to detect early familial ovarian cancer by ovarian ultrasound scan. The influence of coping style was also assessed., Methods: Of 500 women who contacted the nationally advertised screening program, 302 received the scan and participated in the study. Before the screening, they were mailed a questionnaire concerning psychological state, coping style, and anxiety about risk of cancer. Transabdominal ultrasonography and transvaginal ultrasonography with color Doppler imaging were used to detect persistent ovarian lesions and changes in volume. Women were informed of any abnormality immediately and asked to return for another scan after 6 weeks. Those with a persistent ovarian mass were referred for hysterectomy and bilateral oophorectomy. The questionnaire was used to reassess psychological distress after the first ultrasound scan, after re-scanning, and after surgery., Results: The first scan showed negative results for 233 of the 302 women; 69 (23%) had abnormalities in ovarian morphology. Sixty-four of the 69 had a second scan, with negative results for 32 and equivocal results for 12; 20 had surgery because the results of both scans were positive. None of the patients in the screening program were found to have ovarian cancer. After the first scan, psychological distress and worries about cancer were significantly reduced (P < .001) in the women who had negative results. Responses to positive results depended on the baseline coping style and the clinician's appraisal of malignancy potential at the time of the scan. Women who had information-seeking coping styles and those who were referred for surgery had higher levels of distress than other women. At follow-up, the anxiety scores of women who had positive results on both scans but negative results at surgery had returned to baseline levels., Conclusions: The findings suggest that false-positive results in screening are associated with increased distress in the short term, but these adverse effects do not appear to be severe or persistent. Women who had surgery appeared to welcome the certainty that they could never develop ovarian cancer., Implications: The issue of continued surveillance needs to be addressed, since many women expressed the desire to have the scan repeated regularly.