Evaluation of the relationship between serum carcinoembryonic antigen level and treatment outcome in surgically resected clinical-stage I patients with non-small-cell lung cancer

The relationship between preoperative serum carcinoembryonic antigen (CEA) level and treatment outcome for 39 clinical-stage I patients with surgically resected non-small-cell lung cancer (NSCLC) was retrospectively studied. Serum CEA levels were measured with an enzyme-linked immunosorbent assay kit, with the upper limit of normal defined as 6.7 ng/mL based on the 95% specificity level for benign lung disease in our hospital. Patients with serum CEA ≥ 6.7 ng/mL (n = 9) were more likely to have advanced disease at surgery than those with serum CEA < 6.7 ng/mL (n = 30) (77.8% vs 16.7%, p = 0.0049). This increase in disease stage at surgery was mainly due to mediastinal lymph node metastasis. The sensitivity and specificity of serum CEA in the detection of pathological N2 disease were 62.5% and 87.1%, respectively. Survival for the high CEA group was significantly worse than that for the low CEA group (median survival time, 40.2 vs 75.8 months, p = 0.0125). Relapse-free survival for the high CEA group was also poorer than that of the low CEA group (p = 0.0032). In a multivariate analysis, serum CEA level was the most dominant factor affecting relapse-free survival (hazard ratio 6.68, p = 0.0053). These findings suggest that preoperative serum CEA level is useful not only in detection of mediastinal lymph node metastasis, but also in prediction of survival for clinical-stage I patients with NSCLC.