Postoperative serum carcinoembryonic antigen levels in patients with pathologic stage IA nonsmall cell lung carcinoma: subnormal levels as an indicator of favorable prognosis

Background: Elevated serum carcinoembryonic antigen (CEA) levels are sometimes attributable to the production of CEA by malignant cells, and in turn, the antigen itself can enhance the metastatic potential of malignant cells. The authors speculated that low serum CEA levels might be indicative of relatively low levels of malignant cells and a low probability of disease recurrence. This hypothesis led them to investigate whether low CEA levels in serum represented a useful prognostic factor for patients with pathologic Stage IA nonsmall cell lung carcinoma.

Methods: Between 1993 and 2001, 724 patients underwent surgery for NSCLC at Toneyama National Hospital (Toyonaka, Japan). Of these patients, the 242 who were diagnosed with pathologic Stage IA disease were included in the current study. Smoking behavior, gender, age, tumor diameter, disease histology, and preoperative and postoperative serum CEA levels were chosen as study variables, with the cutoff level between subnormal and normal serum CEA levels set at 2.5 ng/mL and the cutoff level between normal and high serum CEA levels set at 5.0 ng/mL. Prognostic indicators were evaluated using a Cox hazard model. In addition, survival probabilities were calculated using the Kaplan-Meier method, and differences in survival were assessed by log-lank analysis.

Results: Subnormal postoperative serum CEA levels were found to be an independent prognostic indicator (hazard ratio, 2.3; 95% confidence interval, 1.1-4.7; P = 0.03 for comparison with patients who had normal CEA levels) on multivariate analysis. Furthermore, the 5-year survival rate was 87% for patients with subnormal postoperative CEA levels (n = 146), compared with 75% for patients with normal postoperative CEA levels (n = 80) and 53% for patients with high postoperative CEA levels (n = 16) (P < 0.0001).

Conclusions: Among patients with pathologic Stage IA NSCLC, those who had an extremely favorable prognosis were distinguished by their subnormal postoperative serum CEA levels.