Clinicopathological characteristics and prognosis of non-lepidic invasive adenocarcinoma presenting as ground glass opacity nodule.

BACKGROUND: Ground glass opacity (GGO) generally associated with the lepidic component of lung adenocarcinoma. However, in some cases, GGO nodules have been associated with invasive adenocarcinomas, where a lepidic component is minimal or absent. The purpose of this study is to evaluate the clinicopathological characteristics and prognosis of non-lepidic invasive adenocarcinoma presenting as GGO nodules.

METHODS: We reviewed computed tomography (CT) images from 168 patients diagnosed with non-lepidic invasive adenocarcinoma classified as stage T1N0M0 (≤3 cm) who underwent curative anatomical resection. Tumors were classified according to radiologic features: 31 were GGO predominant (Group A) and 137 were solid predominant (Group B). The clinicopathological findings and recurrence free survival were used as outcome measures.

RESULTS: The mean percentages of micropapillary and solid component in tumor was higher in Group B than Group A (P<0.001) Pleural invasion and lymphatic invasion were more frequently seen in Group B. The presence of tumors with a micropapillary component was higher in Group B (P=0.040). The 3-year recurrence-free survival was lower in Group B than Group A (80.4% vs. 100%, P=0.019). Risk factors for recurrence such as presence of a micropapillary component and lymphatic invasion were more frequently seen in Group B.

CONCLUSIONS: Non-lepidic invasive adenocarcinoma presenting as GGO has fewer risk factors and better prognosis when compared with those presenting as solid tumors. Therefore, the presence of GGO on chest CT is a good prognostic indicator for lung cancer irrespective of histomorphologic classification.