When screening patients for lung cancer with CT scanning, a more restrictive definition of a positive result could produce fewer false positive diagnoses, with their attendant unnecessary follow-up studies, including biopsies and surgery.
This conclusion, from a study published in the Annals of Internal Medicine, is based on a higher nodule-size threshold for follow-ups from 5 mm to 6 to 8 mm lesion size before starting a more intensive work-up.
"The definition of a positive result is an important part of a screening program. As technology improves, it needs to be reevaluated," stated lead author Claudia I. Henschke, PhD, MD, from the Mount Sinai School of Medicine in New York City.
Dr. Henschke and her colleagues from the International Early Lung Cancer Action Program (I-ELCAP) retrospectively analyzed how raising the threshold for triggering further work-up would affect the frequency of positive results among the 21,136 ELCAP participants who had baseline CT scans performed from 2006 to 2010.
Their analysis showed that subsequent workups were reduced by 36 percent with a 6 mm instead of the 5 mm threshold, by 56 percent with a 7 mm threshold, by 68 percent with an 8 mm threshold, and by 75 percent with a 9 mm threshold.
The analysis showed that lung cancer diagnoses would have been delayed in only a small fraction of the study subjects, and then only by 9 months at most. Ultimately, the researchers argued "the definition of positive result should focus on a size threshold for which the frequency of cancer is sufficiently high and growth on follow-up CT scans can be realistically assessed.
ACSH s Dr. Gilbert Ross added, The editorial accompanying the study pointed out that simply using nodule size is not sufficient for discriminating likely cancer from lesions unlikely to be dangerous. Spiculation, variations in density, and other criteria should be included in a diagnostic algorithm to lend even more predictive capacity to this important screening method, since lung cancer is, and will remain for decades to come, the biggest cancer killer among Americans.
