Hurdles Remain for Lung Cancer Screening Programs

August 13, 2018
Dave Levitan

Low-dose CT screening for lung cancer is recommended for certain individuals, but two new studies highlight some of the limitations and growing pains of a screening program.

Screening for lung cancer using low-dose computed tomography (LDCT) is now recommended for certain individuals based on their smoking history, but two new studies highlight some of the limitations and growing pains of a lung cancer screening (LCS) program. In one, an analysis of conversations between patients and clinicians suggests the recommended “shared decision making” (SDM) model may not be working in practice, while another found a much higher rate of lung cancer overdiagnosis than in previous trials. Both studies were published in JAMA Internal Medicine.

“Although experts disagree on how well the existing evidence suggests an overall net benefit of LCS, consensus has emerged on the importance of shared decision making,” wrote authors of the first study including Daniel S. Reuland, MD, MPH, of the University of North Carolina School of Medicine in Chapel Hill. The US Preventive Services Task Force recommends that screening should not be initiated without SDM involving a thorough discussion of benefits and harms, and the Centers for Medicare & Medicaid Services (CMS) requires an SDM visit before it will cover LCS.

The researchers conducted an analysis of 14 transcribed conversations between physicians and patients presumed to be eligible for LCS that took place between 2014 and 2018. They evaluated these conversations using the OPTION scale (Observing Patient Involvement in Decision Making), where a score of 0 indicates no evidence of SDM and a score of 100 would indicate SDM at the highest skill level.

Nine of the patients were women, and the mean patient age was 63.9 years. Half the cohort were enrolled in Medicare, and eight patients were current smokers. The discussions were had with pulmonologists (eight patients) and with primary care physicians (six patients). The mean total OPTION score for the 14 conversations was only 6, on the scale from 0 to 100 (5 for pulmonologists, 7 for primary care physicians).

None of the conversations met what are considered the minimum skill criteria for 8 of 12 SDM behaviors. The physicians recommended LCS in every conversation, and there was essentially no discussion of potential harms of screening, such as false positives. The mean time spent discussing LCS was 59 seconds, out of a mean visit length of 13:07 minutes.

“Communications about actual harms and benefits of tests and treatments should be a part of the fabric of medicine, which will require continued work on medical education, culture, communication skills, and payment policies,” wrote Rita F. Redberg, MD, MSc, of the University of California, San Francisco, in an accompanying editorial. “This study highlights the important work ahead of us in having informed discussions with patients.”

In the other study, researchers analyzed overdiagnosis rates based on data from the Danish Lung Cancer Screening Trial (DLCST). Previously, the National Lung Cancer Screening Trial (NLST) estimated an overdiagnosis rate of 18.5%, while the Italian Lung Cancer Screening Trial found no evidence of overdiagnosis. The term refers to cancers that appear to be invasive malignant tumors, but grow so slowly that they never would become clinically relevant; increasing biopsy rates and more sensitive screening tests can cause overdiagnosis.

In the new analysis of the 4,104 patients in the DLCST, a total of 96 patients in the screening group were diagnosed with lung cancer (64 detected by screening) compared with 53 patients in the control group who were not screened. The overdiagnosis rate was calculated based on the ratio between the difference in cumulative incidence of lung cancer in the screened and control groups 5 years after the last screening and the cumulative incidence of screen-detected cancers. In this analysis, the overdiagnosis rate was 67.2%.

“Overdiagnosis is an often underappreciated harm of screening,” wrote Mark H. Ebell, MD, MS, of the University of Georgia, and Kenneth W. Lin, MD, MPH, of Georgetown University Medical Center, in an invited commentary. They noted the importance of the SDM model with regard to this result as well. “Patients can make informed choices about LDCT only if practitioners fully disclose all the potential harms of screening, including the risk of overdiagnosis,” they wrote. “It will be important for researchers to continue to refine estimates of lung cancer overdiagnosis, allowing physicians to provide more accurate information to our patients.”

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