Variability in HER2 expression between primary colorectal cancer and corresponding metastases

Purpose This study aimed to investigate the HER2 status of primary colorectal cancer (CRC) and corresponding metastases, and determine the correlation between HER2 and clinicopathological characteristics. Methods We collected the clinicopathological features of 98 CRC patients and 66 patients which were previously evaluated for the KRAS status. The tissue samples of primary CRC tumors ( n = 98), noninvolved colorectal mucosa ( n = 98), paired lymph nodes ( n = 98, 69 patients had positive metastatic nodes), and liver metastases ( n = 22) were evaluated using immunohistochemistry for HER2. The kappa test was used to evaluate the concordance rate of HER2 status. Survival analysis was established according to the Kaplan–Meier method. Results HER2 overexpression was more common in primary tumors among the younger patients ( P