BACKGROUND Focal ground-glass opacity (GGO) is becoming a major concern because of its possible association with lung cancer. In this study, we analyzed the long-term progression of GGOs that persisted for more than 2 years.

METHODS We reviewed focal GGOs identified by thin-section computed tomography that persisted for more than 2 years.

RESULTS We enrolled a total of 114 patients with 175 GGO lesions. The median patient age was 61 years (range, 37-92 years) and 42 (36.8%) patients were male. Mean initial GGO size was 7.8 ± 4.4 mm. Median follow-up duration was 45 months. Forty-six (26.3%) GGOs had significant size increases (≥2 mm in the longest diameter) with a mean volume doubling time of 1041 days. In a multivariate analysis, large size (≥10 mm), the presence of a solid portion (mixed GGO) and old age (≥65 years) were risk factors for significant size increase, with odds ratios (95% CI) of 6.46 (2.69-15.6), 2.69 (1.11-6.95) and 2.55 (1.13-5.77), respectively. GGOs with character changes from pure to mixed or mixed to solid showed more rapid volume expansion.

CONCLUSIONS GGOs which persisted for several years showed an indolent course. Large lesions with a solid portion and GGOs in male or elderly individuals may be cause for more concern, as these factors were associated with size increase. Resection should be considered if GGOs show character changes, as these may be associated with rapid size progression.