In the multivariate analysis which incorporated independent prognostic factors of tumor size, histologic grade, and lymph node metastasis, we found that K-RAS mutations at codon 12 and 13 of exon 2 were both significant with regard to overall survival (p = 0.002 and 0.025) (Table 2). This evidence concerns the gene KRAS and metastatic malignant neoplasm in the lymph nodes.