Using radiation risk models in cancer screening simulations: important assumptions and effects on outcome projections

The Benefits and Harms of Lung Cancer Screening in Individuals With Comorbidities

Introduction

Individuals with a history of smoking and a high risk of lung cancer often have a high prevalence of smoking-related comorbidities. The presence of these comorbidities might alter the benefit-to-harm ratio of lung cancer screening by influencing the risk of complications, quality of life, and competing risks of death. Nevertheless, individuals with chronic diseases are underrepresented in screening clinical trials. In this study, we use microsimulation modeling to determine the impact of chronic diseases on lung cancer benefits and harms.

Methods

We extended a validated lung cancer screening microsimulation model that comprehensively recapitulates an individual's lung cancer development, progression, detection, follow-up, treatment, and survival. We parameterized the model to reflect the impact of chronic diseases on complications from invasive testing, quality of life, and mortality in individuals in five-year age categories between the ages of 50 and 80 years. Outcomes included life-years (LY) gained per 100,000 in patients with chronic obstructive pulmonary disease, diabetes mellitus, heart disease, and history of stroke compared with screening-eligible individuals without comorbidities.

Results

Among individuals between the ages of 50 and 54 years, we found that the presence of a comorbidity altered the LY gained from screening per 100,000 individuals depending on the comorbidity: 4296 LY with no comorbidities; 3462 LY, 3260 LY, 3031 LY, and 3257 LY with chronic obstructive pulmonary disease, heart disease, diabetes mellitus, and stroke, respectively. We observed greater reductions in LY gained in individuals with two comorbidities; we observed similar patterns for individuals between the ages of 55 and 59 years, 60 and 64 years, 65 and 69 years, 70 and 74 years, and 75 and 80 years.

Conclusions

Comorbidities reduce LY gained from screening per 100,000 compared with no comorbidities, and our results can be used by clinicians when discussing the benefits and harms of screening in their patients with comorbidities.

Screening for Lung Cancer: CHEST Guideline and Expert Panel Report

BACKGROUND

Low-dose chest CT screening for lung cancer has become a standard of care in the United States, in large part because of the results of the National Lung Screening Trial (NLST). Additional evidence supporting the net benefit of low-dose chest CT screening for lung cancer, and increased experience in minimizing the potential harms, has accumulated since the prior iteration of these guidelines. Here, we update the evidence base for the benefit, harms, and implementation of low-dose chest CT screening. We use the updated evidence base to provide recommendations where the evidence allows, and statements based on experience and expert consensus where it does not.

METHODS

Approved panelists reviewed previously developed key questions using the Population, Intervention, Comparator, Outcome format to address the benefit and harms of low-dose CT screening, and key areas of program implementation. A systematic literature review was conducted using MEDLINE via PubMed, Embase, and the Cochrane Library on a quarterly basis since the time of the previous guideline publication. Reference lists from relevant retrievals were searched, and additional papers were added. Retrieved references were reviewed for relevance by two panel members. The quality of the evidence was assessed for each critical or important outcome of interest using the Grading of Recommendations, Assessment, Development, and Evaluation approach. Meta-analyses were performed when enough evidence was available. Important clinical questions were addressed based on the evidence developed from the systematic literature review. Graded recommendations and ungraded statements were drafted, voted on, and revised until consensus was reached.

RESULTS

The systematic literature review identified 75 additional studies that informed the response to the 12 key questions that were developed. Additional clinical questions were addressed resulting in seven graded recommendations and nine ungraded consensus statements.

CONCLUSIONS

Evidence suggests that low-dose CT screening for lung cancer can result in a favorable balance of benefit and harms. The selection of screen-eligible individuals, the quality of imaging and image interpretation, the management of screen-detected findings, and the effectiveness of smoking cessation interventions can impact this balance.

Screening for Lung Cancer: CHEST Guideline and Expert Panel Report

BACKGROUND

Low-dose chest CT screening for lung cancer has become a standard of care in the United States in the past few years, in large part due to the results of the National Lung Screening Trial. The benefit and harms of low-dose chest CT screening differ in both frequency and magnitude. The translation of a favorable balance of benefit and harms into practice can be difficult. Here, we update the evidence base for the benefit, harms, and implementation of low radiation dose chest CT screening. We use the updated evidence base to provide recommendations where the evidence allows, and statements based on experience and expert consensus where it does not.

METHODS

Approved panelists developed key questions using the PICO (population, intervention, comparator, and outcome) format to address the benefit and harms of low-dose CT screening, as well as key areas of program implementation. A systematic literature review was conducted by using MEDLINE via PubMed, Embase, and the Cochrane Library. Reference lists from relevant retrievals were searched, and additional papers were added. The quality of the evidence was assessed for each critical or important outcome of interest using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Important clinical questions were addressed based on the evidence developed from the systematic literature review. Graded recommendations and ungraded statements were drafted, voted on, and revised until consensus was reached.

RESULTS

The systematic literature review identified 59 studies that informed the response to the 12 PICO questions that were developed. Key clinical questions were addressed resulting in six graded recommendations and nine ungraded consensus based statements.

CONCLUSIONS

Evidence suggests that low-dose CT screening for lung cancer results in a favorable but tenuous balance of benefit and harms. The selection of screen-eligible patients, the quality of imaging and image interpretation, the management of screen-detected findings, and the effectiveness of smoking cessation interventions can affect this balance. Additional research is needed to optimize the approach to low-dose CT screening.

[Lung screening]

The NLST study found in more than 53,000 (former-) heavy smokers that annual screening with low-dose CT-scan (LDCT) reduced lung cancer mortality and overall mortality by 20% and 6.7% respectively. However, several potential harms of such screening strategy were underlined: over-diagnosis bias, irradiation risk, and the high rate of false-positive results that could lead to futile invasive (and potentially harmful) exams, to impact quality of life, to increase patient's anxiety and costs. All these concerns were largely debated in several recent publications. Most of them concluded in a risk/benefit ratio favoring screening strategy by LDCT. Conversely, most of American academic societies currently recommend LDCT-based lung cancer screening. In France, a taskforce edited a common statement recommending screening smokers or ex-smokers, from 55 to 75years old who have smoked at least 30packs/year. The taskforce also underlined the need for clinical trials aiming to translate screening strategy to the French setting. However, the French Health Authority recently claimed that lung cancer screening was not relevant in the current setting.

Lung Cancer Screening with Chest Computed Tomography in People Living with HIV: A Review by the Multidisciplinary CANCERVIH Working Group

A shift in mortality and morbidity has been observed in people living with human immunodeficiency virus (PLWHIV) from acquired immunodeficiency syndrome (AIDS) to non-AIDS diseases. Lung cancer has the highest incidence rates among all the non-AIDS-defining malignancies and is associated with mortality rates that exceed those of other cancers. Strategies to increase lung cancer survival in PLWHIV are needed. Lung cancer screening with chest LDCT has been shown to be efficient in the general population at risk. The objective of this review is to discuss lung cancer screening with chest computed tomography in PLWHIV. Lung cancer screening in PLWHIV is feasible. Whether PLWHIV could benefit from an age threshold for screening that is earlier than the minimum age of 55 years usually required in the general population still needs further investigation. Studies evaluating smoking cessation programs and how they could be articulated with lung cancer screening programs are also needed in PLWHIV.

Breast cancer screening for women with Down syndrome: lessons learned

This study examined mammogram reports of women with Down syndrome (DS) treated in the largest medical facility specifically serving adults with DS in the United States. Records of 684 women and results of 993 mammograms were reviewed, including 902 screening and 93 diagnostic mammograms. Only 2 (0.7%) women had a diagnosis of breast cancer. This study found a low rate of breast cancer among women with DS, a finding which is consistent with previous studies. The financial cost per finding was high, the benefit of the mammograms questionable, and the potential for harm greater. With less than 1% of the women with DS in this study developing breast cancer, further discussion is recommended to assess whether mammography is a beneficial, cost-effective part of health maintenance for women with DS.

Imaging-based screening: understanding the controversies

OBJECTIVE

The goals of this article are to provide an overview of controversial aspects of imaging-based screening and to elucidate potential risks that may offset anticipated benefits.

CONCLUSION

Current controversial topics associated with imaging-based screening include false-positive results, incidental findings, overdiagnosis, radiation risks, and costs. Alongside the benefits of screening, radiologists should be prepared to discuss these additional diagnostic consequences with providers and patients to better guide shared decision making regarding imaging-based screening.

CT lung cancer screening: where are we heading to?

SUMMARY 

Lung cancer screening has been the subject of controversies since the 1970s. After failure of chest x-ray and sputum cytology examination to decrease lung cancer mortality, there was a 15-year period of disillusion. Low-dose CT scan of the thorax provided a renewal of interest with prospective studies followed by randomized trials of which four have been published. Only one, the NLST trial involving 53,000 participants is positive with a 20% reduction in lung cancer specific mortality rate. The European studies are by far smaller, the largest being the Nelson study with 15,000 participants. There are some shortcomings and biases that must be known and well explained to the future participants to a lung cancer screening program. The cost/benefit ratio remains to be better analyzed.

Prioritizing examination-centered over patient-centered dose reduction: a hazard of institutional "benchmarking"

OBJECTIVE

The purpose of this article is to evaluate whether examination-specific radiation dose metrics reliably measure an institution's success in reducing cancer risks.

MATERIALS AND METHODS

We projected health benefits from dose-reduction programs in a hypothetical institution that sought to decrease exposures from abdominopelvic CT. Using modeling techniques to project radiation-induced cancer risks and tertiary center data to inform the institution's abdominopelvic CT age distribution, we compared a program in which effective doses were reduced equally (from 10 to 7 mSv) across all scans with programs in which dose reduction was age dependent. For each program, we projected lethal cancers averted, life expectancy gained, and average institutional dose achieved. Markov Chain Monte Carlo methods were used to estimate uncertainty in projections.

RESULTS

The analysis's age distribution drew from 20,979 CT scans; 39% were from patients 65 years old and older. To illustrate trends yielded, if all patients in the hypothetical institution underwent 7-mSv (instead of 10-mSv) scans, we projected the maximum number of lethal cancers averted to be seven per 100,000 patients, and maximum life expectancy gained to be 0.26 days per patient, when averaged over the institution's population. When restricting dose reduction (from 10 to 7 mSv) to patients younger than 65 years, benefits were slightly lower (five lethal cancers averted per 100,000 patients and 0.22 days per patient gained); however, the average institutional dose was substantially higher (8.2 mSv). Although dose reduction in patients 65 years old and older accounted for only 16% of possible institutional life expectancy gains, this patient group contributed disproportionately (39%) to the institution's average dose.

CONCLUSION

Institutional examination-specific dose metrics can be misleading, because the least-benefited patients may contribute disproportionately toward "improved" averages.

Patients with testicular cancer undergoing CT surveillance demonstrate a pitfall of radiation-induced cancer risk estimates: the timing paradox

PURPOSE

To demonstrate a limitation of lifetime radiation-induced cancer risk metrics in the setting of testicular cancer surveillance-in particular, their failure to capture the delayed timing of radiation-induced cancers over the course of a patient's lifetime.

MATERIALS AND METHODS

Institutional review board approval was obtained for the use of computed tomographic (CT) dosimetry data in this study. Informed consent was waived. This study was HIPAA compliant. A Markov model was developed to project outcomes in patients with testicular cancer who were undergoing CT surveillance in the decade after orchiectomy. To quantify effects of early versus delayed risks, life expectancy losses and lifetime mortality risks due to testicular cancer were compared with life expectancy losses and lifetime mortality risks due to radiation-induced cancers from CT. Projections of life expectancy loss, unlike lifetime risk estimates, account for the timing of risks over the course of a lifetime, which enabled evaluation of the described limitation of lifetime risk estimates. Markov chain Monte Carlo methods were used to estimate the uncertainty of the results.

RESULTS

As an example of evidence yielded, 33-year-old men with stage I seminoma who were undergoing CT surveillance were projected to incur a slightly higher lifetime mortality risk from testicular cancer (598 per 100 000; 95% uncertainty interval [UI]: 302, 894) than from radiation-induced cancers (505 per 100 000; 95% UI: 280, 730). However, life expectancy loss attributable to testicular cancer (83 days; 95% UI: 42, 124) was more than three times greater than life expectancy loss attributable to radiation-induced cancers (24 days; 95% UI: 13, 35). Trends were consistent across modeled scenarios.

CONCLUSION

Lifetime radiation risk estimates, when used for decision making, may overemphasize radiation-induced cancer risks relative to short-term health risks.

From randomized trials to the clinic: is it time to implement individual lung-cancer screening in clinical practice? A multidisciplinary statement from French experts on behalf of the French intergroup (IFCT) and the groupe d'Oncologie de langue francaise (GOLF)

Background

Despite advances in cancer therapy, mortality is still high except in early-stage tumors, and screening remains a challenge. The randomized National Lung Screening Trial (NLST), comparing annual low-dose computed tomography (LDCT) and chest X-rays, revealed a 20% decrease in lung-cancer-specific mortality. These results raised numerous questions. The French intergroup for thoracic oncology and the French-speaking oncology group convened an expert group to provide a coherent outlook on screening modalities in France.

Methods

A literature review was carried out and transmitted to the expert group, which was divided into three workshops to tackle specific questions, with responses presented in a plenary session. A writing committee drafted this article.

Results

The multidisciplinary group favored individual screening in France, when carried out as outlined in this article and after informing subjects of the benefits and risks. The target population involves subjects aged 55–74 years, who are smokers or have a 30 pack-year smoking history. Subjects should be informed about the benefits of quitting. Screening should involve LDCT scanning with specific modalities. Criteria for CT positivity and management algorithms for positive examinations are given.

Conclusions

Individual screening requires rigorous assessment and precise research in order to potentially develop a lung-cancer screening policy.

Comparative effectiveness and child health

Comparative effectiveness research is expected to play an important role in future clinical and policy decision making in the US; however, the application of comparative effectiveness methodologies to child health requires special attention to aspects of health and healthcare that are specific to children. These special considerations include the role of parent/caregiver as joint decision maker and co-participant in many types of interventions, how the effectiveness of an intervention varies by age and developmental stage, and the difficulties in translating short-term data from childhood into projected effectiveness over the lifespan. Each aspect of comparative effectiveness, such as conducting new studies, synthesizing existing evidence, emphasizing real-world settings, considering multiple decision makers, and measuring patient-relevant outcomes, will require expanded definitions when considered in the context of child health. This paper discusses how comparative effectiveness methods and concepts will differ when applied to child health and suggests a potential role for decision analysis as a method to synthesize data and project long-term outcomes. The initiation of comparative effectiveness studies for children represents an exciting opportunity to provide evidence that can guide clinical and policy decisions for child health.