Tumor histology affects the accuracy of clinical evaluative staging in primary lung cancer.

Objective: Pathological examination of lung cancer often reveals a more advanced stage than clinical stage. The objective of this study was to evaluate whether the association between clinical and pathologic stages depends on tumor histology.

Methods: This retrospective study enrolled patients who had undergone major lung resections and systemic lymph node dissections (1990-2004). In total, 483 patients had adenocarcinoma and 225 had squamous cell carcinoma.

Results: Clinical and pathologic N-status were significantly different in patients with adenocarcinoma (p<0.0001) but not in those with squamous cell carcinoma. Patients with adenocarcinoma were more likely to be upstaged from clinical N0 disease to pathologic N2 disease than those with squamous cell carcinoma (p = 0.04). Of those patients with adenocarcinoma, surgical procedure, clinical N-status, metastatic pathologic N2 stations and curability were significant prognostic factors. It is of interest, however, that a similar statistically significant difference could not be shown in patients with squamous cell carcinoma. Furthermore, multivariate analysis demonstrated that clinically detectable N2 disease and multiple pathologic N2 stations significantly affected the poorer prognosis in adenocarcinoma. Adenocarcinoma patients with clinically undetectable N2 disease had significantly better 5-year survival than those with clinically detectable N2 disease (p<0.0001), although this was not the case for patients with squamous cell carcinoma (p = 0.81).

Conclusion: In adenocarcinoma patients with pathologic N2 disease, clinical N-status and metastatic pathologic N2 stations were significant prognostic factors. A similar difference was not found in patients with squamous cell carcinoma. Adenocarcinoma and squamous cell carcinoma appear to have different tendencies for lymph node metastasis.