Pulmonary adenocarcinomas appearing as part-solid ground-glass nodules: Is measuring solid component size a better prognostic indicator?

Objective To assess whether measuring the solid portion of adenocarcinomas appearing as part-solid ground-glass nodules (GGNs) can predict a patient's prognosis accurately and how the prognosis corresponds to that of solid nodules. Methods 501 patients (solid nodule group, 304; part-solid GGN group, 197) underwent curative surgery for stage I adenocarcinomas. Maximal diameters of the whole lesion including ground-glass opacities (D-whole) and solid components only (D-solid) were measured on CT. Disease-free survival (DFS) and overall survival (OS) were calculated from the date of surgery. Results D-solid was a significant prognostic factor in the part-solid GGN group, while D-whole was not. Part-solid GGNs with D-solid <= 2 cm showed significantly better DFS (P=0.016) and OS (P=0.004) than solid nodules; however, those with D-solid>2 cm did not show a significant difference. Hazard ratio (HR) for increase in D-solid was significantly greater in part-solid GGNs than in solid nodules (P=0.009). For OS, HR for increase in D-solid was greater in part-solid GGNs than in solid nodule, which was marginally not significant (P=0.060). Conclusion D-solid was better than D-whole for prognosis prediction of adenocarcinomas appearing as part-solid GGNs. In addition, the influence of D-solid on prognosis in the part-solid GGN group was greater than in the solid nodule group.