Nodule volume, doubling time stratifies lung cancer risk

By Shreeya Nanda, Senior medwireNews Reporter

An interim analysis of the NELSON study reveals the significance of nodule size and volume doubling time for the risk of cancer in patients who have undergone low-dose computed tomography (CT) lung cancer screening.

“These results imply that use of lung cancer probability-based thresholds for nodule size and growth and volumetry in nodule management protocols can improve lung cancer detection, and reduce unnecessary follow-up CTs, invasive diagnostic procedures, and costs”, remark Nanda Horeweg (Erasmus University Medical Center, Rotterdam, the Netherlands) and co-workers.

Recognising that “the main challenge in CT screening for lung cancer is the high prevalence of pulmonary nodules and the relatively low incidence of lung cancer”, the researchers used data from the NELSON trial “to quantify the probability of developing lung cancer within 2 years of CT screening, based on measurements of lung nodule diameters, volumes, and volume doubling times.”

The NELSON trial includes 15,822 individuals aged between 50 and 75 years with a high lung cancer risk as a result of smoking at least 15 cigarettes per day for more than 25 years or at least 10 cigarettes per day for more than 30 years. Participants were randomly assigned to receive low-dose CT screening at increasing intervals or to receive no screening.

This prespecified analysis published in The Lancet Oncology included data on 9681 non-calcified nodules detected in 7155 individuals who underwent at least one round of screening.

Lung cancer probability was not significantly increased for patients with a nodule volume below 100 mm³ or for those with a maximum nodule diameter below 5 mm, at 0.6% and 0.4%, compared with patients with no detected nodules, at 0.4%.

The probability of lung cancer was intermediate in patients with a nodule volume of 100 to 300 mm³ or a diameter of 5 to 10 mm, at 2.4% and 1.3%, respectively. Participants with a nodule volume above 300 mm³ or a diameter greater than 10 mm had a high risk of lung cancer, at 16.9% and 15.2%, respectively.

Volume doubling time was also associated with the likelihood of lung cancer in individuals whose largest nodule was between 50 and 500 mm³. Patients with slow-growing nodules (volume doubling time ≥600 days) or nodules that were stable, shrunken or resolved at follow-up had a less than 1% risk of developing lung cancer within 2 years of screening.

However, probability of lung cancer significantly increased to 4.0% for participants whose volume doubling time was 400 to 600 days, and to 9.9% for those with a doubling time of up to 400 days.

The authors recommend immediate diagnostic work-up for patients whose nodule volume puts them in the high-risk category, while for those with intermediate-volume nodules, the findings of volume doubling analysis should also be taken into account.

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