Differential prognostic significance of extralobar and intralobar nodal metastases in patients with surgically resected stage II non-small cell lung cancer

Abstract

Objectives: We sought to determine the prognostic significance of extralobar nodal metastases versus intralobar nodal metastases in patients with lung cancer and pathologic stage N1 disease.

Methods: A retrospective review of a prospectively maintained lung resection database identified 230 patients with pathologic stage II, N1 non-small cell lung cancer from 1997 to 2011. The surgical pathology reports were reviewed to identify the involved N1 stations. The outcome variables included recurrence and death. Univariate and multivariate analyses were performed using the R statistical software package.

Results: A total of 122 patients had extralobar nodal metastases (level 10 or 11); 108 patients were identified with intralobar nodal disease (levels 12-14). The median follow-up was 111 months. The baseline characteristics were similar in both groups. No significant differences were noted in the surgical approach, anatomic resections performed, or adjuvant therapy rates between the 2 groups. Overall, 80 patients developed recurrence during follow-up: 33 (30%) of 108 in the intralobar and 47 (38%) of 122 in the extralobar cohort. The median overall survival was 46.9 months for the intralobar cohort and 24.4 months for the extralobar cohort (P < .001). In a multivariate Cox proportional hazard model that included the presence of extralobar nodal disease, age, tumor size, tumor histologic type, and number of positive lymph nodes, extralobar nodal disease independently predicted both recurrence-free and overall survival (hazard ratio, 1.96; 95% confidence interval, 1.36-2.81; P = .001).

Conclusions: In patients who underwent surgical resection for stage II non-small cell lung cancer, the presence of extralobar nodal metastases at level 10 or 11 predicted significantly poorer outcomes than did nodal metastases at stations 12 to 14. This finding has prognostic importance and implications for adjuvant therapy and surveillance strategies for patients within the heterogeneous stage II (N1) category.