Real-world findings from a Veterans Affairs population reinforce the need for personalized decision-making about lung cancer screening using validated risk-stratification models, researchers said.
Using the Bach risk tool for assessing lung cancer risk in veterans screened at eight academic VA centers, nearly 5,600 veterans in the lowest risk quintile needed to be screened to prevent one lung cancer death.
Meanwhile, the number of false-positive cases per death averted was 2,221.
Patients in the highest quintiles of lung cancer risk had significantly more lung cancers diagnosed supporting the model’s ability to stratify risk in this population, wrote Tanner J. Caverly, MD, of the VA Center for Clinical Management Research in Ann Arbor, Michigan, and colleagues.
Their findings, published in JAMA Internal Medicine, bolster those from a VA screening trial published last March, showing a very high false-positive rate associated with lung cancer screening.
The false-positive rate in that population was around 58%, which was more than twice the false-positive rate seen in the National Lung Screening Trial.
The U.S. Preventive Services Task Force recommends lung cancer screening with low-dose CT for high-risk people between the ages of 55 and 80, defined as having a greater than 30 pack-year cumulative smoking history and having quit within the past 15 years for those no longer smoking (grade B recommendation).
The journal’s editor, Rita F. Redberg, MD, of the University of California San Francisco (UCSF), told MedPage Today that while it is increasingly clear that the risks of screening outweigh the benefits for smokers and former smokers considered to have a low risk for lung cancer, whether this message has reached screening candidates is not so clear: “People in low-risk groups need to know that they have a much greater risk for harm and a low chance for benefit, and this harm is not insignificant. Being told that you might have lung cancer and having to have additional testing represents a significant harm.”
In an editorial published with the current study, Redberg and Michael Incze, MD, also of UCSF, wrote that the future of lung cancer screening “depends on our ability to reexamine and refine our approach to patient selection and clearly communicate risks and benefits of screening.”
The study cohort consisted of 2,106 veterans screened for lung cancer at eight academic VA centers during a 3-month period in the spring of 2015 as part of the Veterans Health Affairs Lung Cancer Screening Demonstration Project.
Annual baseline lung cancer mortality risk was estimated using the Bach risk model, which is a validated tool calculating sex, smoking duration, duration of abstinence from smoking, and number of cigarettes smoked per day to estimate lung cancer risk. Participants were separated into risk quintiles and assessed for lung cancer cases observed, number needed to screen (NNS) per lung cancer death prevented, and number of false-positive results and downstream diagnostic procedures.
Among the main findings:
- Patients in higher quintiles of lung cancer risk had significantly more lung cancers diagnosed (4.8 lung cancers per 1,000 in quintile 1 versus 29.7 per 1,000 in quintile 5)
- Initial screens were least effective for veterans in quintile 1 (the lowest lung cancer risk) with number needed to screen of 6,903 and most effective for veterans in quintile 5, with number needed to screen of 687
- The rates of false-positive results and downstream evaluations did not differ significantly across risk quintiles (P=0.52 and P= 0.15 for trend, respectively)
- The overall 56.2% rate of false-positive results requiring tracking remained relatively stable across risk quintiles (95% CI 53.1%-62.6% in quintile 1 versus 95% CI 51.9%-61.5% in quintile 5), as did the overall 2.0% rate of false-positive results requiring downstream diagnostic evaluations (95% CI 0.3%-2.6% in quintile 1 versus 95% CI 1.7%-5.2%)
“We found that even given these very high false-positive rates, the overall balance of pros and cons among patients at high lung cancer risk still surpasses those of most established cancer screening programs,” the researchers wrote.
Redberg said that even in the high-risk quintile, the number needed to screen of 687 to avert a single lung cancer death was relatively high.
“Our history of shared decision-making is not the best, and we need to do a better job of conveying the benefits and risks of screening in all risk groups,” she added.
Funding for the research was provided by the U.S. Department of Veterans Affairs Quality Enhancement Research Initiative.
Caverly and co-authors reported no relevant relationships with industry related to the study.
F. Perry Wilson, MD, MSCE Assistant Professor, Section of Nephrology, Yale School of Medicine and Dorothy Caputo, MA, BSN, RN, Nurse Planner