The long-term outcomes of follow-up care for ground-glass opacity (GGO) need to be clarified.
Between 2000 and 2005, 226 patients with pure or mixed GGOs of 3 cm or smaller in size were registered. The CT findings and changes in the findings during the follow-up period and the outcomes of the 226 patients were subsequently reviewed.
Overall, 124 patients underwent resections, 57 did not receive follow-up examinations after 68 months because of stable disease or disease reduction and 45 were continuing to receive follow-up examinations. Thirty-nine patients showed tumor growth during the follow-up period. Among the patients with a ratio of the diameter of consolidation relative to the tumor diameter (CTR) >0, all the cases with tumor growth were identified within 3 years; meanwhile, more than 3 years were required to identify tumor growth in 16% of the patients with a CTR =0. Aggressive cancer occurred in 4% of the patients with a CTR =0 and in 70% of the patients with a CTR >25%. Aggressive cancer was observed in 46% of the patients whose CTR increased during the follow-up period and in 8% of the patients whose tumors increased in size.
A higher CTR and an increase in the CTR during the follow-up were associated with invasive cancer. A follow-up period of 3 years is considered to be adequate for judging tumor growth in patients with a CTR >0, while a longer follow-up period might be needed for patients with a CTR =0.