Treatment Outcomes of Stereotactic Body Radiotherapy for Ground Glass Opacity Nodules and Solid Lung Cancer.

[PURPOSE] Disease control outcomes of ground glass opacity nodules (GGNs) treated with stereotactic body radiotherapy (SBRT) were evaluated with comparing to solid lung cancer.

[MATERIAL AND METHODS] Patients who received SBRT for primary lung cancer with maximum tumor diameter of 5 cm or smaller between July 2006 and February 2012 were retrospectively reviewed.

[RESULTS] A total of 169 primary lung cancer (GGNs, 40; solid lung cancer, 129) in 151 patients (age, 55-92; median, 79) were treated with SBRT of 48-62.5 Gy in 4-5 fractions (mean 50.3 Gy). Median follow-up time was 52 months (3-180 months). For GGNs and solid lung cancer, 5-year local failure free rates (LFF) were 94% and 74% (p = 0.0223), 5-year regional failure free rates (RFF) were 95% and 79% (p = 0.0293), 5-year distant failure free rates (DFF) were 86% and 77% (p = 0.0803), and 5-year overall survival rates (OS) were 73% and 40% (p < 0.0001). In multivariable analysis, tumor appearance of solid lung cancer was the significant unfavorable factor for LFF, RFF, and OS. When GGNs were classified into two groups according to consolidation to maximum tumor diameter ratio (CTR), 5-year LFF, RFF, and DFF were 100%, 100%, and 93% for GGNs with CTR < 0.5, and 71%, 78%, and 62% for GGNs with CTR ≥ 0.5.

[CONCLUSIONS] LFF and RFF after SBRT were significantly better in GGNs compared to solid lung cancer. However, local, regional, and distant failure were not uncommon in GGNs with CTR ≥ 0.5, as were solid lung cancer. Disease control outcomes of SBRT was favorable in GGNs with CTR < 0.5.