P1.08-005 Stratification of pStage I Lung Adenocarcinoma by the Scoring System Based on Prognostic Factors

Abstract

In Stage I lung cancer, tumor size and PL factors are only reflected by the TNM staging system. However, other clinicopathological factors have the potential to influence recurrence and prognosis, especially in pStage I lung adenocarcinoma. This study aimed to evaluate prognostic factors, and to thereby stratify pStage I lung adenocarcinoma patients. A total of 203 patients who underwent curative resection for Stage I invasive adenocarcinoma, from 2006 to 2013, were retrospectively reviewed. 18F-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) was performed in 194 patients and the maximum standardized uptake value (SUVmax) of the tumor was calculated. Invasive adenocarcinoma was classified into 3 predominant subtypes (lepidic, papillary and others) according to the IASLC/ATS/ERS classification. The associations between various clinicopathological factors and recurrence were evaluated, and disease-free survival (DFS) was analyzed. Twenty-eight patients had recurrent disease during the follow-up period (mean; 59.3±25 months). Uni-variable analysis showed male gender, smoking history >20 pack-years, BMI≦20, CEA>5ng/ml, T classification, tumor size>20mm, predominant histologic subtype (lepidic, papillary, others), pleural invasion, vascular invasion, and SUVmax>3.0 to be significantly associated with worse DFS. On multivariable analysis, tumor size>20mm (P=0.006), papillary predominant (P=0.023), other predominant (P=0.008), and SUVmax>3.0 (P=0.008) were extracted as independent prognostic factors associated with worse DFS. Predictive variables were scored as follows; tumor size>20mm (1 point), papillary predominant (1 point), other predominant (2 points) and SUVmax >3.0 (1 point). Patients were classified into 3 risk groups (low-risk; 0-2, intermediate-risk; 3, high-risk; 4) according to their aggregate scores. The 5-year DFS rate was 91% in the low-risk group, 55% in the intermediate group and 36% in the high-risk group. The 5-year DFS rates during the same period in our institute were 88% in pStage IA, 69.5% in pStage IB, 53% in pStage II, and 38% in pStage IIIA patients. Therefore, the DFS rate in the intermediate-risk group was comparable to that of pStage II, and the DFS rate in the high-risk group was comparable to that of pStage IIIA. In Stage I lung adenocarcinoma, tumor size, SUVmax and histologic subtypes were suggested to be prognostic factors. This scoring system may predict the groups, such as patients with pStage II and IIIA, requiring platinum based post-operative chemotherapy.