New Subsolid Pulmonary Nodules in Lung Cancer Screening: The NELSON Trial

Introduction: Low-dose computed tomography (LDCT) lung cancer screening is recommended in the United States. While new solid nodules after baseline screening have a high lung cancer probability at small size and require lower size cutoff values than baseline nodules, there only is limited evidence on management of new subsolid nodules. Methods: Within the Dutch-Belgian randomized controlled LDCT lung cancer screening trial (NELSON), 7557 participants underwent baseline screening between April 2004 and December 2006. Participants with new subsolid nodules detected after the baseline screening round were included. Results: In the three incidence screening rounds, 60 new subsolid nodules (43 [72%] part-solid, 17 [28%] nonsolid) not visible in retrospect were detected in 51 participants, representing 0.7% (51 of 7295) of participants with at least one incidence screening. Eventually, 6% (3 of 51) of participants with a new subsolid nodule were diagnosed with (pre-)malignancy in such a nodule. All (pre-)malignancies were adenocarcinoma (in situ) and diagnostic workup (referral 950, 364, and 366 days after first detection, respectively) showed favorable staging (stage I). Overall, 67% (33 of 49) of subsolid nodules with an additional follow-up screening were resolving. Conclusions: Less than 1% of participants in LDCT lung cancer screening presents with a new subsolid nodule after baseline. Contrary to new solid nodules, data suggest that new subsolid nodules may not require a more aggressive follow-up.