Every interaction with patients is an opportunity to change the course of their lives. In the context of screening for disease, every encounter is an opportunity to detect the precursors or early changes that signal early pathophysiology. Smoking status and age are the factors that currently determine eligibility for lung cancer screening with low-dose computed tomography (CT) scans, and we are learning that the CT scan offers valuable insight into the structures of the thorax, which predicts disease other than lung cancer. Low-dose CT scans provide a window of opportunity to intervene on early lung cancers but also to understand other disease processes that may affect an individual patient in the future.1
Our understanding of this powerful tool to address early pathophysiology and then intervene is at an early stage. As the technology evolves to better quantify and understand the images we acquire through advanced analytics machine learning, we will be able to use imaging screening to accomplish more than one goal.2 A future in which one scan tells us about not only lung cancer risk, but also risk for several other conditions is closer than one might realize.
Low-Dose CT Screening and Emphysema in Asymptomatic Patients
A study recently reported in Clinical Imaging by Steiger et al—and reviewed in this issue of The ASCO Post—reported on the prevalence of emphysema in the International Early Lung Cancer Action Project (I-ELCAP) study population. It highlighed that in 76.5% of patients with radiographic emphysema, no prior diagnosis of chronic obstructive pulmonary disease (COPD) was present.3 Diagnosis of COPD can be confusing, and recently we have seen advances in understanding risk factors, but it is known that we often underdiagnose and misdiagnose COPD.4 Spirometry with a post-bronchodilator forced expiratory volume in 1 second/forced vital capacity less than 0.70 and/or the lower limit of normal is the gold standard to confirm COPD diagnosis; however, respiratory symptoms and radiographic changes in the lungs can be discordant with spirometry findings. Screening spirometry is recommended only for patients with COPD risk factors and symptoms,5 further complicating the diagnosis of early or mild COPD.
“In the context of screening for disease, every encounter is an opportunity to detect the precursors or early changes that signal early pathophysiology.”— Inga T. Lennes, MD, MPH, MBA
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In the Steiger et al study, patients with undiagnosed COPD and radiographic emphysema were more likely to be younger men with lower pack-year smoking histories and less comorbid cardiac disease and no history of lung cancer—a population of patients who may not frequently interact with health care, given their relatively healthy status and younger age. Finding radiographic emphysema in this population may present an opportunity to open the door to explore possible mild, previously unrecognized symptoms and referral for further testing. COPD is also an independent risk factor for lung cancer. Although it is unclear whether early pharmacologic treatment of COPD is effective, we do know that early detection of COPD is important to promote tobacco cessation interventions, biomass exposure reduction, pulmonary rehabilitation, and increased physical activity—all factors crucial to prevent the progression of the disease.6
Low-Dose CT Screening and Coronary Artery Calcification
Smoking impacts health beyond lung cancer, and coronary artery calcification is a common significant finding in low-dose CT for lung cancer screening.7 The link between coronary artery calcification and coronary artery disease is well established, and coronary artery calcification is a known independent predictor of future cardiovascular events. In one study, 25.9% of patients who underwent lung cancer screening with low-dose CT were found to have moderate to severe coronary artery calcification, and almost half of those identified went on to have further cardiac evaluation with other noninvasive diagnostic testing and/or referral to a cardiologist.8
Thus, identification of coronary artery calcification on screening studies represents an area of potential vulnerability, as there is still variation in the rates of further intervention and testing. As reporting of coronary artery calcification improves and becomes standardized in low-dose CT reports, management of patients with this significant risk factor may improve their health.
Clinical Implications
The study by Steiger et al focused on identifying radiographic emphysema as a possible signal for previously undiagnosed COPD and asserted that low-dose CT may serve as another modality to screen for early or asymptomatic disease. In addition to COPD and coronary artery disease, smoking is a well-established risk factor for stroke, aortic aneurysm, and peripheral vascular disease. Low-dose CT offers an opportunity to address tobacco use in current smokers and recent quitters. The ability to identify any smoking-related disease during screening provides important information for changing the trajectory of future health, with an emphasis on tobacco use treatment and cessation.
Prior to the COVID-19 pandemic, telehealth research began to investigate novel ways of deploying smoking cessation services.9 Since the pandemic, the promise and possibilities of remote technologies to deliver health care have accelerated greatly, and behavioral counseling interventions conducted via telehealth (telephone or video) are well suited to these new modes of care, particularly in the context of low-dose CT. Future research should take advantage of innovative changes implemented during the public health crisis.
“In addition to reducing lung cancer mortality, expanded screening criteria hold the promise of finding early changes such as emphysema and coronary artery calcification.”— Inga T. Lennes, MD, MPH, MBA
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The Smoking Cessation at Lung Examination (SCALE) collaboration is an initiative sponsored by the National Cancer Institute to conduct research on tobacco use treatment in low-dose CT–eligible smokers with a 30 or more pack-year history. The data generated in the SCALE initiative will be valuable to draw connections between smoking cessation rates and low-dose CT deployment as well as to design successful interventions.10
Although the I-ELCAP population in the Steiger et al study included younger patients (≥ age 40) with a current or former smoking history, until recently, the U.S. Preventive Services Task Force (USPSTF) guidelines recommended screening with low-dose CT for patients between the ages of 55 and 80 with a 30-pack year smoking history. In March 2021, the USPSTF issued new guidelines to include younger patients, between the ages of 50 and 80, with a lower, 20-pack year, smoking history.
The USPSTF estimates that following the new guideline may lead to a 13% greater reduction in lung cancer deaths and may narrow significant racial disparities in screening.11 Black individuals have a higher risk of lung cancer compared with White persons, including at lower levels of smoking. By extending the screening criteria, more people are eligible for screening, with the increase in the eligible population being enriched for non-Hispanic Black persons and women. In addition to reducing lung cancer mortality, expanded screening criteria hold the promise of finding early changes such as emphysema and coronary artery calcification, which portend future smoking-related disease at a time when we can deliver meaningful and accessible interventions to improve patients’ future overall health.
Dr. Lennes works in Massachusetts General Hospital (MGH), Dana Farber/Harvard Cancer Center, Boston, and is Director of the Pulmonary Nodule Clinic at MGH.
DISCLOSURE: Dr. Lennes holds stock or other ownership interests in InfiniteMD, has received honoraria from Blue Cross and Blue Shield of Massachusetts and UnitedHealthcare, and has served as a consultant or advisor to Kyruus.
REFERENCES
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3. Steiger D, Siddiqi MF, Yip R, et al: The importance of low-dose CT screening to identify emphysema in asymptomatic participants with and without a prior diagnosis of COPD. Clin Imaging 78:136-141, 2021.
4. Lamprecht B, Soriano JB, Studnicka M, et al: Determinants of underdiagnosis of COPD in national and international surveys. Chest 148:971-985, 2015.
5. Global Initiative for Chronic Obstructive Lung Disease: 2020 Global Strategy for the Prevention, Diagnosis, and Management COPD. Available at https://goldcopd.org/gold-reports/. Accessed July 26, 2021.
6. Laucho-Contreras ME, Cohen-Todd M: Early diagnosis of COPD: Myth or a true perspective. Eur Respir Rev 29:200131, 2020.
7. Ravenel JG, Nance JW: Coronary artery calcification in lung cancer screening. Transl Lung Cancer Res 7:361-367, 2018.
8. Mendoza DP, Kako B, Digumarthy SR, et al: Impact of significant coronary artery calcification reported on low-dose computed tomography lung cancer screening. J Thorac Imaging 35:129-135, 2020.
9. Lennes IT, Luberto CM, Carr AL, et al: Project Reach: Piloting a risk-tailored smoking cessation intervention for lung screening. J Health Psychol 25:1472-1482, 2020.
10. Park ER, Chiles C, Cinciripini PM, et al: Impact of the COVID-19 pandemic on telehealth research in cancer prevention and care: A call to sustain telehealth advances. Cancer 127:334-338, 2021.
11. U.S. Preventive Services Task Force: Lung cancer: Screening. Available at https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/lung-cancer-screening. Accessed July 26, 2021.
