Lung cancer patients showing pure ground-glass opacity on computed tomography are good candidates for wedge resection

Abstract

Small lung cancers frequently have been detected in mass screening by computed tomography (CT) in recent years. Suitability of limited resection for these small lung cancers remains controversial. One hundred patients who underwent sublobular limited resection (wedge resection or segmentectomy) for lung cancer in our hospital from 1981 to 2002 were analyzed retrospectively. From CT findings, tumors were classified into two groups; pure ground-glass opacity (PGGO) and non-PGGO. Patients included 44 women and 56 men, and ages ranged from 40 to 92 years (mean, 71.0). Histologic types included 76 adenocarcinomas, 21 squamous cell carcinomas, and 3 large cell carcinomas. Clinical stages included 83 stage IA and 17 stage IB. By high-resolution CT, 27 tumors (27%) showed PGGO; at postoperative histopathologic examination, all of these were localized bronchioloalveolar carcinomas. Diameter of tumors showing PGGO was 9.3±3.5 mm (mean±S.D.); that of non-PGGO tumors was 21.2±13.7 mm. Overall and lung cancer-specific 5-year survival rates in all patients were 58.0 and 64.8%, respectively. Overall 5-year survival rate with small adenocarcinomas (≤20 mm) was 93.7%, significantly better than 24.8% with larger adenocarcinomas (P<0.0001). No intrathoracic recurrence or distant metastasis has been observed in PGGO tumors. For peripheral localized bronchioloalveolar carcinoma showing PGGO, wedge resection appears to be the best operation. Definitive study of more patients with longer follow-up is needed.

Introduction

The present standard operation for primary lung cancer is considered to be lobectomy with systematic lymphadenectomy. However, suitability of limited resection has been examined by several investigators. Outcome of segmentectomy first was reported in a large number of patients by Jensik et al. [1] in the 1970s. They performed segmentectomy for 168 stage I peripheral lung cancers, obtaining a survival rate of 53% at 5 years after surgery; this survival rate was comparable to that with lobectomy. However, a later study [2] from the same institution demonstrated a higher recurrence rate with segmentectomy than with lobectomy in stage I lung cancer. In that study, the rate of locoregional recurrence was 22.7% (15/66) after segmentectomy versus 4.9% (5/103) after lobectomy. A randomized controlled trial comparing limited resection (segment or wedge) with lobectomy for T1N0 non-small cell lung cancer (NSCLC) was carried out by the Lung Cancer Study Group [3] beginning in the 1980s.That study clearly found outcome with limited resection to be inferior to that with lobectomy, in terms of both survival and locoregional recurrence. Since then, limited resection for stage IA lung cancer generally has been avoided, except for patients with impaired cardiopulmonary function.

On the other hand, small cancers with diameters less than 1 cm frequently have been found in the periphery of the lung since introduction of mass screening by computed tomography (CT) in recent years [4], [5], [6]. Most such small cancers are not detectable in chest radiopraphs; by CT, they show ground-glass opacity (GGO) [7]. Most of them are diagnosed pathologically as localized bronchioloalveolar carcinoma or as atypical adenomatous hyperplasia (AAH) [8], [9], a precancerous lesion. Further, development of video-assisted thoracoscopic surgery (VATS) can permit relatively noninvasive wedge resection of small lung nodules in a short operating time, which is particularly important for poor-risk patients [10], [11], [12]. However, indications for sublobular resection and curability of these small lung cancers by such procedures still are controversial. Avoidance of excessive surgery for small lung cancers detected by increasingly wide spread mass CT screening will become an important issue. We therefore sought to identify the clinicopathologic characteristics of lung cancers suitable for wedge resection by retrospectively analyzing outcomes of patients with primary NSCLC removed by sublobular resection without systematic dissection of lymph nodes.