Comparison of mutational changes in involved N1 lymph nodes with those in primary tumors in stage II non-small cell lung cancer: A pilot study

Objectives: Surgical resection is the standard treatment for stage II non-small cell lung cancer, but recurrence rates approach 60%. This study compared mutational changes in involved lymph nodes and primary tumors from patients with stage II non-small cell lung cancer to determine whether risk factors for recurrence could be identified. Methods: Forty patients with resected stage II non-small cell lung cancer (excluding T3 N0 disease) were studied. Microdissection was performed on primary tumors and lymph nodes. Analysis was performed across 9 genomic loci by using polymerase chain reaction amplification. The ratio of fractional allelic loss between involved lymph nodes and primary tumors was used to stratify patients into high-risk (fractional allelic loss ratio of ≥1) and low-risk (fractional allelic loss ratio of <1) groups. Results: The median age of the patients was 68 years (range, 42-85 years). Median follow-up was 30 months. Fractional allelic loss was greater in patients with squamous carcinomas compared with that in adenocarcinomas, but survival was similar (35 vs 39 months). The median survival was 35 months in high-risk patients and was not reached in low-risk patients (P = .3). Disease-free survival was 24 months in high-risk patients and was not reached in low-risk patients (P = .35). In the subset with adenocarcinoma (n = 18), median survival was 24 months in the high-risk group; no deaths occurred in low-risk patients (P = .01). Also, disease-free survival was 14 months in high-risk patients and was not reached in the low-risk patients (P = .05). Conclusions: Squamous cancers demonstrate greater mutational changes than adenocarcinomas; this does not affect outcome. The patients with low-risk adenocarcinomas demonstrated superior outcomes compared with those of other patients. These results should be confirmed in larger studies.