Prognostic Implications of HER2 Overexpression in Locally Advanced Rectal Cancer Treated with Neoadjuvant Chemoradiation
Purpose: The clinicopathological value of human epidermal growth factor 2 (HER2) overexpression in colorectal cancer is debatable. The aim of the present study is to evaluate the relationship between HER2 and clinicopathological variables of rectal cancer patients after neoadjuvant chemoradiation.
Methods: Clinicopathological data of 99 patients with rectal adenocarcinoma who received radical surgery after neoadjuvant chemoradiation were analyzed retrospectively. HER2 protein expression and HER2 gene copy number were determined by immunohistochemistry and silver in situ hybridization, respectively. The tumor response to chemoradiation was evaluated with TNM staging and tumor regression grading.
Results: Twenty-five (25.3%) tissues showing an immunohistochemistry score of 2+ or 3+ were determined as high HER2 protein expression, and HER2 gene amplification was detected in 12 (12.6%) samples. Overall HER2 gene amplification was significantly correlated with HER2 expression (P = 0.004, Spearman’s coefficient = 0.289). HER2 overexpression and gene amplification did not correlate with tumor response of TNM downstaging and tumor regression grading, disease-free survival, and overall survival. In comparison of HER2 expression in 68 pretreatment and postoperative specimens, 61 cases (89.7%) showed agreement (kappa coefficient = 0.730, P < 0.001).
Conclusion: HER2 overexpression in locally advanced rectal cancer was not associated with tumor response to neoadjuvant chemoradiation and cancer related survival.
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