Research suggests lung cancer risk increases with size of new solid nodules

Recent findings published in the American Journal of Roentgenology suggest that new solid lung nodules may increase a patient's risk of developing lung cancer. According to this data from the National Lung Screening Trial (NLST), new nodules found with the help of low-dose CT (LDCT) scans may be more dangerous than baseline nodules.  

"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 lead author Paul Pinsky, PhD, from the National Institutes of Health (NIH). "This is consistent with the idea of cancerous nodules detected at baseline being, on average, slower growing than new cancerous nodules."  

Pinsky and his team later conclude that lung cancer risk is associated with the size (diameter) of new and differed from baseline nodules, increasing cancer risk. Study methods leading to this conclusion required researchers to classify nodules detected at "postbaseline time 1 [T1] and time 2 [T2]" as new or preexisting on the basis of comparing LDCT screening results, according to the study.   

A total of 25,002 participants with a history of smoking and all between the ages of 55 and 74 underwent baseline LDCT or chest radiography screenings conducted by the NLST (T1). A majority of those participants returned for required follow-ups screenings one or two years after (T2). The relationship between nodule size and stage, histologic findings and survival was also examined, according to Pinsky.  

It's crucial to note that although findings from the two post-baseline screening rounds conducted have already been published. However, an analysis distinguishing between preexisting and new nodules was not.  

According to study results, at both time 1 (T1) and time 2 (T2), 2.6 percent of participants had new solid nodules.  

"Cancers associated with new nodules had significantly poorer survival than did those associated with baseline nodules and were significantly less likely to be adenocarcinoma," Pinsky said in regards to study findings.   

Additional findings include:  

• 66.6 percent of people linked with baseline nodules has a 5-year survival rate, which fell to 51.1 percent for nodules detected at follow-up rounds.  
• 53 percent of new solid nodules were greater than six millimeters, 29.5 percent were six to 10 millimeters, and 17.1 percent were less than 10 millimeters in size.  
• Post follow-up, lung cancer risk (defined as diagnosis within 2 years of baseline) increased from 1.1 percent for nodules greater than four millimeters to 24 percent for nodules less than 20 millimeters in size. 
• Compared with solid nodules detected at baseline, the cancer risk was higher for new solid nodules four to six millimeters and six to eight millimeters, but lower for new nodules less than 20 millimeters in size.

Overall, Pinsky and his team hope that this study will help encourage longer-term follow ups of new lung nodules to further examine their progression from nodule to cancer over time.