Risk factors for occult nodal metastasis in clinical T1N0 lung cancer: a negative impact on survival.

Background: The application of CT imaging has increased the identification of patients with clinical T1N0 (cT1N0) lung cancer. The optimal management strategy for these early stage lung cancers remains unclear. We analyzed the impact of occult nodal metastasis on cT1N0 lung cancer patients.

Methods: We studied patients with cT1N0 lung cancer enrolled in our database from January 1995 to December 2002. Preoperative staging was confirmed by review of CT and PET scan studies. Pathology specimens were reviewed. Multivariate analysis was performed to determine the risk of occult nodal involvement. Kaplan-Meier method was applied to analyze survival.

Results: Two hundred and ninety-seven patients with cT1N0 disease were identified. Fifty-eight percent of patients were pathological T1N0. Overall, 15% of patients had occult nodal metastasis. Logistic regression analysis demonstrated a three-fold increase in the risk of having pathologic stage II or stage III disease with every 1.0 cm increase in tumor size (odds ratio 3.2; 95% CI: 2.3-4.6). Multivariate analysis demonstrated tumor size to be a significant predictor of nodal metastasis (adjusted odds ratio 3.5; 95% CI: 2.4-5.1). Median survival was different between pathological stage I (96.3 months), stage II (41.4 months), and stage III (36.1 months) disease (p=0.002).

Conclusion: Clinical T1N0 tumors are often understaged. The risk of occult nodal disease increases with tumor size, and this occult disease negatively impacts survival. Because of the limitations of clinical staging, we believe that lobectomy and lymph node analysis should be offered to cT1N0 lung cancer patients to provide accurate staging and to optimize multimodality adjuvant treatment of lung cancer.