High epidermal growth factor receptor expression in metastatic lymph nodes may be more prognostic than in primary tumor for colorectal cancer survival

Abstract

15031 Background: High epidermal growth factor receptor (EGFR) expression in the primary tumor is prognostic for poor survival in colorectal cancer (CRC). Discordance of EGFR expression has been noted in the paired primary versus nodal or distant metastasis. The aim of this study was to evaluate prognostic value of elevated EGFR expression in nodal or distant metastasis versus primary tumor tissue. Methods: Tissue microarrays from 93 surgically resected CRC primaries were analyzed for EGFR expression using immunohistochemistry along with 49 paired metastatic lymph nodes (MLN) and 19 distant metastases. Logistic regression, Kaplan-Meier survival curves, and the log-rank test were used to describe the association of tumor stage and survival with EGFR level dichotomized to low expression (0,1) versus high expression (2,3). Results: High EGFR expression in primary tumor, MLN and distant metastasis were 18%, 24%, and 21% respectively. In stage III/IV patients, eight of 14 patients (57%) with EGFR+ primary tumors did not show high expression in MLN, and 6/35 (17%) patients with EGFR- primary tumors gained high EGFR expression in MLN. High EGFR expression in primary tumor was associated with stage III/IV versus stage I/II disease (odds ratio 5.5, P = 0.012) and therefore predicted poor survival (P = 0.046). High EGFR expression in the primary or in distant metastasis was not associated with poor survival, whereas only high EGFR expression in MLN was associated with poor survival in stage III and stage IV disease combined or separately (Table 1) Conclusions: High EGFR expression in MLN appears more accurate in predicting survival than its expression in the primary or distant metastasis, thus may aid in selecting patients to receive adjuvant treatment incorporating anti-EGFR therapy. Prognostic values of discordant EGFR expression in different tissues warrants further investigation. Log rank P-values comparing overall survival for high EGFR expression in primary and metastatic tis Stage III/IV(n=49) Stage III(n=30) Stage IV(n=19) Pirmary tumor 0.332 0.795 0.161 Metastastic lymph node 0.005 0.002 0.014 Distant metastasis 0.246 No significant financial relationships to disclose.