Screening is essential to reducing deaths from lung cancer, a condition which, due to high rates of late-stage diagnosis, is the leading cause of cancer-related mortality worldwide. The United States Preventative Services Task Force (USPSTF) recommends low-dose computed tomography (LDCT) screening for individuals aged 55 to 80 who either currently smoke or have quit within the past 15 years and have a history of 30 or more pack years, a pack year being the number of packs smoked per day multiplied by the number of years over which a person has smoked. In this interview with i3 Health, Ping Yang, MD, PhD, Professor of Epidemiology at Mayo Clinic College of Medicine and Science, discusses her study's finding that some groups excluded by the USPSTF criteria are at equally high risk of death from their lung cancer as those eligible for screening.
What led you to investigate a comparison of five-year survival rates for patients with lung cancer eligible or ineligible for screening according to the USPSTF criteria?
Ping Yang, MD, PhD: In 2014, the USPSTF recommended screening for lung cancer in individuals aged 55 to 80 years with a smoking history of 30 or more pack years who currently smoke or have quit within the past 15 years. Soon after this recommendation was issued, a few studies reported that nearly two thirds of newly diagnosed lung cancer patients did not meet the USPSTF criteria. Moreover, our previous study revealed that the largest subgroups of lung cancer patients not meeting the screening criteria were those who either had not smoked in more than 15 years ("long-term quitters") or were in the age group of 50 to 54 years ("younger age") at the time of diagnosis. In the current study, we assessed these two subgroups for overall survival outcome, hoping that they would fare better than those meeting the screening criteria. However, our finding is that that is not the case.
Can you comment on the significance of your results?
Dr. Yang: The goal of a disease screening effort is to reduce its death rate, yet our results indicate that the two largest patient groups outside the screening criteria actually experienced the same risk of death. For this reason, we believe that people who otherwise meet the screening criteria but are long-term quitters or are of younger age should be screened. This expanded inclusion will enhance the screening program goal of maximizing the reduction of lung cancer mortality.
What was the basis for the current USPSTF criteria?
Dr. Yang: The current USPSTF guidelines were based on a reported 20% reduction in lung cancer mortality associated with screening high-risk individuals with LDCT as found by the National Lung Screening Trial. This trial took nearly a decade from its inception to the release of final results. Although a positive finding supported screening with LDCT scan, the information substantiating the trial was dated, partly due to the much higher proportion of former smokers and long-term quitters who have emerged in recent decades.
What impact would result from lowering the age cutoff and including long-term quitters in the recommendations?
Dr. Yang: This is a very important question and a sensitive point. As they are now, the USPSTF guidelines for lung cancer screening face at least three major issues: high false positive rates, potential for overtreatment, and unknown health hazards from exposure to LDCT. These same issues would apply to the long-term quitters and younger-age people should they be included. In order to optimize the benefit-to-harm ratio, there is a critical need for testable biological markers with close to 100% accuracy in identifying at-risk individuals.
About Dr. Yang
Ping Yang, MD, PhD, Professor of Epidemiology at Mayo Clinic College of Medicine and Science in Scottsdale, Arizona, has been the principal investigator and co-investigator of many lung cancer studies. She is an Associate Editor of the Journal of Thoracic Oncology. Her research, which focuses on the genomic and clinical epidemiology of cancer, seeks ways to reduce cancer's incidence and mortality, increase early-stage cancer detection and diagnoses, and optimize treatment and post-treatment quality of life.
For More Information
Luo Y, Luo L, Wampfler JA, et al (2019). 5-year overall survival in patients with lung cancer eligible or ineligible for screening according to US Preventive Services Task Force criteria: a prospective, observational cohort study. Lancet Oncol. [Epub ahead of print] DOI:10.1016/S1470-2045(19)30329-8
Transcript edited for clarity. Any views expressed above are the speaker's own and do not necessarily represent those of i3 Health.