Redefinition of positive CT result for lung cancer explored

(HealthDay)—Increasing the threshold for defining a positive result in computed tomography (CT) screening for lung cancer could reduce the need for further work-up but must be weighed against the potential for delayed diagnosis, according to a study published in the Feb. 19 issue of the Annals of Internal Medicine.

To examine whether more restrictive CT screening thresholds would affect the frequency of positive results and lead to potential delays in the diagnosis of lung cancer, Claudia I. Henschke, Ph.D., M.D., of the Mount Sinai School of Medicine in New York City, and colleagues conducted a prospective cohort study involving 21,136 participants with baseline CT screening. The current definition of positive result was any parenchymal, solid, or part-solid, noncalcified nodule of 5.0 mm or larger.

Using current thresholds, the researchers found that 16 percent of participants had a positive result. The frequency of positive results was 10.2, 7.1, 5.1, and 4.0 percent, respectively, for a threshold of 6.0, 7.0, 8.0, and 9.0 mm. The use of these higher thresholds would have correlated with reductions of 36, 56, 68, and 75 percent, respectively, in work-up. Lung cancer diagnoses would have been delayed by a maximum of nine months for 0, 5.0, 5.9, and 6.7 percent of cancer cases, respectively.

"The definition of positive result needs to be continually prospectively evaluated and updated in light of emerging evidence from on-going screening programs to reduce unnecessary surgery for nonmalignant pulmonary nodules and reduce potential harms of the diagnostic work-up, while maximizing the diagnosis and treatment of curable cases of lung cancer," the authors write.

Two authors have pending and issued patents, some of which are licensed to General Electric Healthcare. One author disclosed financial ties to AstraZeneca.