Lung Cancer Risk Increased With Presence of Solid Lung Nodules Post-Baseline

11/13/17

A recent study found that new solid lung nodules identified post-baseline may increase a patient’s risk of developing lung cancer, published in the American Journal of Roentgenology (November 2017;209[5]:1009-1014).

Low-dose CT lung cancer screening is becoming a routine part of clinical practice. Evaluation of nodules identified by such screening is critical to the prognoses of patients.

Paul Pinsky, PhD, National Institutes of Health, and colleagues conducted a study to examine the frequency and clinical outcomes of new lung nodules found at two post-baseline annual screenings (T1 and T2) compared with those detected at baseline. A total of 25,002 patients were included and underwent baseline low-dose CT screening examination and either a T1 or T2 screen. After patients were followed for lung cancer incidence and mortality, researchers assessed the incidence of new nodules and their associated lung cancer risk by nodule size.

Results of the study showed that at both T1 and T2, 2.6% of patients had new solid nodules. The 5-year survival rate for patients with baseline nodules was 66.6%, which decreased to 51.1% for those with nodules detected at either T1 or T2.

Researchers noted that 53% of new nodules were less than 6 mm, 29.5% were 6-10 mm, and 17.1% were at least 10 mm in diameter. After follow-up, researchers found that risk of lung cancer (defined as diagnosis within 2 years of baseline) increased from 1.1% for nodules less than 4 mm to 24.0% for nodules at least 20 mm in diameter.  

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In comparison to solid nodules detected at baseline, risk of lung cancer was higher for new solid nodules that were 4-6 mm and 6-8 mm, but lower for new nodules that were at least 20 mm in diameter.

Additionally, researchers acknowledged that lung cancers associated with new nodules were more predictive of poor survival than those associated with baseline nodules. Cancer associated with new nodules were also less likely to be adenocarcinomas.

"When we compared characteristics of lung cancers associated with new nodules versus baseline nodules, the latter were significantly more likely to be adenocarcinoma and to have significantly improved survival than the former," said Dr Pinsky in a press release (November 8, 2017). "This is consistent with the idea of cancerous nodules detected at baseline being, on average, slower growing than new cancerous nodules."—Zachary Bessette