Expression of carcinoembryonic antigen in peripheral- or central-located small cell lung cancer: Its clinical significance

Background: Small cell lung cancer (SCLC) has a higher percentage of hilar masses than other histological types of lung cancer. The primary site is us ually adjacent to the hilum, but we often observe primary sites in the peri pheral lung field. In this study, our objectives were to elucidate whether peripheral-located small cell lung cancer (PSCLC) is an independent entity and whether it differs clinically from central-located small cell lung canc er (CSCLC). Methods: We reviewed the clinical and pathological features of 52 patients treated at Kagawa Medical University Hospital between 1987 and 1996 with a diagnosis of SCLC. We defined CSCLC as a tumor whose primary site is locate d in the segmental bronchi or more proximally and PSCLC as a tumor located distal to the subsegmental bronchi. Twenty-one PSCLC patients and 31 CSCLC patients were identified. Kaplan-Meier survival curves were constructed and comparisons were made between PSCLC and CSCLC by the log-rank test. The ca rcinoembryonic antigen (CEA) level was also evaluated in each group. Results: Although the percentage of limited disease (LD) in the patients wi th PSCLC was higher than that in the patients with CSCLC, the 3-year surviv al rate of PSCLC tended to be worse than that of CSCLC (9% for patients wit h PSCLC and 29% for those with CSCLC). Survival curves of patients with PSC LC also tended to be worse than those of patients with CSCLC, not only in t he limited disease group but also in the extensive disease (ED) group. In a ddition, the mean CEA value in patients with PSCLC was higher than that in patients with CSCLC (p < 0.001), whereas the neuron specific enolase (NSE) level was not significantly different between PSCLC and CSCLC. The median s urvival of patients with pretherapeutic CEA titers of <greater than>5 ng/ml was significantly shorter than that in patients with CEA levels <5 ng/ml. Conclusion: These findings suggest that the survival of SCLC patients with a high CEA level was significantly shorter than that of patients with a low CEA level. In addition, CEA levels in PSCLC patients were significantly hi gher than those in CSCLC patients. However, the survivals of LD or ED patie nts with PSCLC and CSCLC were not statistically different.