Prognostic value of ground-glass opacity found in small lung adenocarcinoma on high-resolution CT scanning.

OBJECTIVE

This study was undertaken to investigate the value of the ground-glass opacity (GGO) area found on high-resolution computed tomography (HRCT) scanning as a preoperative prognostic indicator.

PATIENTS AND METHODS

We studied 104 patients with small-sized lung adenocarcinoma, 20 mm or less in diameter, between 1995 and 1999. Three independent radiologists semi-quantitatively scored the extent of GGO on HRCT as greater than or less than 50%. Three independent pathologists semi-quantitatively scored the extent of the bronchioloalveolar carcinoma (BAC) component of the tumor on histologic examination as greater than or less than 50%. As no relapse occurred in patients with GGO greater than 50%, multivariate analysis of this prognostic factor was not possible.

RESULTS

Fifty patients were scored as having both BAC and GGO greater than 50%, 36 as both BAC and GGO less than 50%, and 16 as BAC greater than 50% and GGO less than 50%. In only two patients (1.9%), BAC less than 50% was overestimated on HRCT as GGO greater than 50%. The sensitivity and specificity of GGO to BAC were 76 and 95%, respectively. The 3 year-relapse-free survival rates in each group of 52 patients with GGO greater than and less than 50% were 100 and 72%, respectively, after a median follow-up of 24 months. Univariate analysis indicated that both GGO and BAC areas were significantly correlated with cancer relapse (P=0.005 and P=0.002). The multivariate analysis revealed an independent prognostic influence of the BAC area on relapse-free survival (P=0.015, relative risk=0.07).

CONCLUSIONS

To date there has been no relapse among the 52 patients with GGO greater than 50%. This novel classification based on the semiquantitative analysis of GGO area on HRCT should become an useful independent preoperative indicator when deciding on operative procedure, and to predict the potential of relapse in patients with small adenocarcinoma arising from the peripheral lung.