August 30, 2021 — Shortening the follow-up interval by one month for indeterminate lesions found on CT lung cancer screening — from six to five — translates into better patient outcomes, according to a study published August 19 in the Journal of the American College of Radiology.
The results could change the way clinicians care for patients with lung findings classified as Lung-RADS 3 (probably benign), wrote a group led by Mehrad Bastani, PhD, of Stanford University.
“Our [study supports] the notion that both individuals and physicians [should be] highly encouraged to ensure the diagnostic follow-up examinations for subjects with Lung-RADS category 3 nodules are implemented earlier or no later than the current recommended six-month interval,” the team wrote.
The American College of Radiology’s Lung CT Screening Reporting and Data System (Lung-RADS) was developed to standardize diagnostic follow-up of suspicious findings on CT lung cancer screening. But the timing of this follow-up, particularly for category 3 (probably benign) and 4A (suspicious), remains open to debate.
“The National Lung Screening Trial (NLST) demonstrated that screening with low-dose CT (LDCT) reduces [lung cancer]-specific mortality by 20% compared with chest radiography among high-risk patients,” the group wrote. “However, the NLST had no standard follow-up protocol for suspicious pulmonary nodules of unknown clinical significance (aka, indeterminate findings).”
Bastani and colleagues evaluated the effectiveness of various follow-up intervals for Lung-RADS 3 and 4A lesions. They used the Lung Cancer Outcome Simulator (LCOS) — a tool developed by the Cancer Intervention and Surveillance Modeling Network Consortium — to estimate outcomes among a simulated 1960 population level cohort of 1 million men and women for different follow-up periods, based on the U.S. Preventive Services Task Force (USPSTF) lung cancer screening guidelines.
The current recommended follow-up interval for Lung-RADS 4A lesions is three months, and the modeling study confirmed that this timeframe is best. But for lesions categorized as Lung-RADS 3, the group determined that five months rather than the recommended six-month follow-up translated into better outcomes in a simulated cohort of 1 million people.
|Impact of reducing follow-up from 6 to 5 months for indeterminate lung lesions on CT|
|6-month follow-up||5-month follow-up||Difference|
|Mortality reduction||6.89%||6.97%||0.08 percentage points|
|Deaths averted||3,253||3,217||36 deaths|
|Screen-detected cases of cancer||14,561||14,582||21 cases|
|No. of LDCT scans and diagnostic follow-ups per death averted||738||730||8|
|Life-years gained||44,068 life years||44,667 life-years||599 life-years|
The study shows that patients with indeterminate lesions on low-dose CT lung cancer screening should be urged to follow through on follow-up, according to the researchers.
“Patients with Lung-RADS 3 nodule findings are encouraged to avoid any follow-up delays despite their low malignancy risks,” they concluded.