Importance of tumor size in resectable stage III-N2 non-small cell lung cancer

The 8th TNM edition classifies stage III-N2 disease as IIIA and IIIB based on a tumor size cutoff of 5 cm. However, the importance of tumor size on survival in patients with resectable stage III-N2 disease has not been analyzed systematically.

Survival analysis based on tumor size (>5 cm vs ≤ 5 cm) for 255 consecutive patients with nonbulky (maximal lymph node diameter of 1.5 cm) stage III-N2 non-small cell lung cancer treated with surgery in our institution.

Ninety patients (35.3%) underwent induction chemoradiation therapy (n = 72, 28%) or induction chemotherapy (n = 18, 7%), and 165 patients underwent primary surgery followed by adjuvant chemotherapy (n = 52, 32%), adjuvant chemoradiation therapy (n = 47, 29%), or adjuvant radiation therapy (n = 14, 13.2%). After a median follow-up of 6.5 years, the overall survival was 46.5% at 5 years and 28.9% at 10 years. In tumors 5 cm or less, there was no difference in survival between patients treated with induction or adjuvant therapy. However, in tumors greater than 5 cm, the survival was significantly better after induction therapy compared with adjuvant therapy or surgery alone. Pathologic multi-station N2 disease was more frequently detected in tumors greater than 5 cm (31% vs 18% in tumors ≤5 cm, P = .042), and the rate of R1 resection was lower after induction therapy (2.2% vs 8.5% in primary surgery, P = .048).

These results support the redefinition of tumors greater than 5 cm with resectable N2 disease to stage IIIB. This change should help to refine the multimodality approach for stage III-N2 lung cancer.