Estimating Overdiagnosis After Implementation of Lung Cancer Screening in Community-Based Healthcare Systems

PROJECT SUMMARY/ABSTRACT
Low-dose computed tomography (LDCT) has been accepted as an efficacious population-based
approach for lung cancer screening (LCS) based on findings from the National Lung Screening
Trial (NLST) which demonstrated a 20% reduction in lung cancer deaths. These findings and
subsequent recommendations from the US Preventative Services Task Force in December
2013 along with expanded guidelines in 2021, resulted in LCS via LDCT being implemented in a
variety of community and academic settings starting in 2014. However, as with any screening
program, there are concerns about the potential for LCS to lead to overdiagnosis of lung cancer.
Overdiagnosis is the detection of cancers through cancer screening that never would have been
diagnosed in the absence of cancer screening and would never lead to significant patient
morbidity or mortality in a patient’s lifespan if left untreated. Any diagnosis of lung cancer
generally causes the patient to engage in aggressive treatment and overdiagnosis may result in
anxiety, serious physical harm, unnecessary losses in quality of life, and financial health-care
costs. The variability, and uncertainty over the potential LCS-related harms, has led to extensive
debate regarding the balance between harms and benefits of LCS. Although the strongest
evidence for overdiagnosis comes from randomized control trials (RCTs) with long-term follow-
up, patients participating in RCTs are generally not representative of those in community-based
settings. Compared to NLST participants, individuals participating in community based LCS
settings are more likely to be older, to currently smoke, and have a high comorbid burden.
Specifically, participants receiving LCS care in community-based settings were more likely to
have COPD, asthma, bronchiectasis, chronic bronchitis, diabetes, and hypertension compared
to NLST participants, thus increasing the likelihood of death from another disease before the
lung cancer progresses. These differences suggest that the magnitude of overdiagnosis may be
very different from estimates derived from RCTs. Observational studies are needed to provide a
source of robust evidence to inform the existence and magnitude of overdiagnosis in lung
cancer for individuals receiving LCS care outside of an RCT. As LCS participation continues to
evolve, this evidence is needed to inform future clinical and policy decision making. Therefore,
the primary objective of this study is to produce a range of estimates of overdiagnosis
among patients diagnosed with lung cancer who participated in the LCS process in
community-based healthcare settings.

Grant Number: 1R03CA292991-01
NIH Institute/Center: NIH
Principal Investigator: Nikki Carroll