ObjectivePresentation with multiple ground glass opacities (GGOs) is an increasingly common occurrence, and the optimal management of these lesions is unclear. Active surveillance has been increasingly adopted as a management strategy for other low-grade malignancies. We hypothesized that active surveillance could be a feasible and safe option for patients with multiple GGOs. MethodsPatients with ≥2 GGOs (ground glass predominant, <50% solid, ≤3 cm) were enrolled in a multi-institutional registry and prospectively followed up on active surveillance with computed tomography scans every 6 to 12 months. Each GGO was catalogued and measured individually at each follow-up visit. ResultsTarget accrual was met, with 337 patients from 23 institutions. The mean age was 70 years (interquartile range, 65-77 years), and 74% were women. Most were former (70%) or current (9%) smokers, with a mean exposure of 30 pack-years (interquartile range [IQR], 15-44 pack-years). Half of the patients (51%) had a previous lung cancer, and the majority (86%) were already under surveillance at the time of study entry. The median number of GGOs per patient was 3 (IQR, 2-5), with a total of 1467 GGOs under surveillance. The median GGO size was 0.9 cm (IQR, 0.7-1.3 cm). Most GGOs were 0.5 to 1 cm in size. ConclusionsActive surveillance, rather than immediate intervention, was an acceptable option to patients, and accrual to this registry trial was feasible. Safety endpoints and long-term outcomes will be assessed in the planned 5-year follow-up in accordance with the protocol.