Objective: Ground-glass opacity (GGO) of the lung is being frequently detected by thin section computed tomography scan. However, the long term management of detected GGO is still unclear. To establish follow-up plans, we performed the clinical and radiological review to identify the factors that are closely associated with GGO growth.
Methods: We retrospectively analyzed computed tomography images of 125 GGOs that were stable for 3 months between 1999 and 2006 at the Cancer Institute Hospital, Tokyo. To identify factors that affect the roentgenological growth, the time to GGO growth curve by Kaplan-Meyer method was evaluated in terms of gender, age, smoking, initial size, existence of a solid part, GGO density, location, multiplicity, and lung cancer history by univariate and multivariate analyses.
Results: The median observation period was 1048 days (177-3269) and 26 of 125 GGOs (21%) grew. The estimated growth population for 5 years was 30%. The growth was more frequently seen in the elderly (p = 0.017), in part-solid GGO (p < 0.01) and in GGO of larger than 10 mm (p < 0.01, logrank test). By multivariate analysis, initial size (p < 0.01, Cox's model) and history of lung cancer (p = 0.017, logistic model) were independent factors that were significantly associated with GGO growth. Fifty GGOs that were 10 mm or smaller and without a lung cancer history did not grow within 3.5 years.
Conclusions: After initial management and 3 month follow-up, larger size (more than 10 mm) and a history of lung cancer are risk factors for GGO growth, and therefore should be considered when making a follow-up plan.