Is There a Prognostic Difference Between Stage IIIA Subgroups in Lung Cancer?

Background: Treatment of stage IIIA lung cancer remains controversial because it includes a very heterogeneous group of patients. The purpose of our study was to compare survival between stage IIIA subsets and to externally validate our results with another center's database.

Methods: Patients with completely resected stage IIIA/B lung cancer were retrospectively analyzed. There were 424 patients with stage IIIA and 82 patients with stage IIIB (T3/4 N2) (study cohort). Stage IIIA was divided into 2 subsets according to the tumor localization and tumor size (T3 N1-T4 N0/1, IIIA-T group; n = 308) and the extension of nodal disease (T1/2 N2, IIIA-N2 group; n = 116). The study cohort results were used to create a model for stage IIIA patients, which was validated with another center's database (validation cohort).

Results: The multivariate analyses showed age, stage IIIB, and pN2 were independent negative prognostic factors (P < .0001). Survival at 5 years was 51.3% (median, 64 months) for patients in the IIIA-T group and was 25.7% (median, 31 months) in the IIIA-N2 patients (hazard ratio, 1.834; P < .0001). There was no statistical difference in survival between the IIIA-N2 and stage IIIB groups (25.7% vs 25.3%, P = .442). The created model was performed on patients in the validation cohort as a model IIIA-T (T3 N1-T4 N0/1, n = 139) and model IIIA-N2 (T1/2 N2, n = 104). Model IIIA-T patients had a statistically better survival rate than model IIIA-N2 patients (median, 62 months vs 37 months; hazard ratio, 1.707, P < 0.001).

Conclusions: There is a prognostic difference between stage IIIA subgroups in lung cancer patients who undergo surgical treatment.