Prioritizing Reevaluation of Lung Cancer Screening Risk Thresholds

Regular reevaluation of risk thresholds is key to improving lung cancer screening efficiency, and the United States Preventive Services Task Force (USPSTF) may benefit from externally validated models in the development of their screening guidelines, according to a report published in Annals of Internal Medicine.

Researchers from the National Cancer Institute in Bethesda, Maryland, and the International Agency for Research on Cancer in Lyon, France, raised several questions related to the current USPSTF risk thresholds for lung cancer screening guidelines.

Using 2005 and 2015 National Health Interview Survey results, the researchers estimated the number of ever-smokers between the ages of 50 and 80who were eligible for lung cancer screening according to 1 of 3 risk thresholds: the National Comprehensive Cancer Network (≥1.3%-NCCN) threshold, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Model threshold (≥1.5%-PLCO_M2012), and the Lung Cancer Death Risk Assessment Tool threshold (≥1.2%-LCDRAT).

Per the USPSTF guidelines, 8 million ever-smokers in 2015 were eligible for screening. However, after applying the 3 risk thresholds, an additional 4.6 million, 3.3 million, and 1 million ever-smokers became eligible for screening, a 57% increase for the ≥1.3%-NCCN threshold (95% CI, 49%-64%), a 41% increase for the ≥1.51%-PLCO_M2012 threshold (95% CI, 34%-47%), and a 12% increase for the ≥1.2%-LCDRAT threshold (95% CI, 5%-20%), respectively.  

Of note, the ≥1.3%-NCCN and the ≥1.5%-PLCO_M2012 thresholds selected the same proportion and an even smaller proportion of ever-smokers as the USPSTF guidelines (38% and 35%, respectively).

Screening efficiency for the USPSTF guidelines was estimated as a number needed to screen of 194 and 133 false-positive screening results per prevented death. When compared with the USPSTF guidelines, the efficiency and the false-positive screening results per prevented death may be improved only for the ≥1.2%-LCDRAT threshold. However, more deaths might be prevented using all 3 thresholds than the USPSTF guidelines.

Higher thresholds are required to recalibrate the risk thresholds for the selection of 8 million ever-smokers (≥2.19% for PLCO_M2012 or ≥1.33% for LCDRAT). At these thresholds, both efficiency and false-positive screening results per prevented death may be improved compared with USPSTF guidelines.

“Compared with the USPSTF guidelines, the ≥1.30%-NCCN and ≥1.51%-PLCO_M2012 thresholds would screen millions more US ever-smokers, possibly at lower efficiency and with more [false-positive screening results],” the researchers wrote. “This is due to large reductions in smoking over time.”

The researchers concluded that “[r]isk thresholds should be revaluated regularly as population characteristics change to ensure they maximize the number of deaths prevented with acceptable efficiency and minimal harms.”

Reference

Landy R, Cheung LC, Berg CD, Chaturvedi AK, Robbins HA, Katki HA. Contemporary implications of US Preventive Services Task Force and risk-based guidelines for lung cancer screening eligibility in the United States [published online June 4, 2019]. Ann Intern Med. doi:10.7326/M18-3617