Objective: To investigate the consistence of human epidermal growth factor receptor 2 (HER-2) expression in resection samples and biopsy samples from rectal cancer and its clinical implication.
Methods: Clinical data and tissue samples of 544 rectal cancer patients who received surgical resection at Peking University Cancer Hospital from September 2009 to March 2012 were collected and analyzed retrospectively. Immunohistochemical method was used to test HER-2 expression in both surgical resection samples and preoperative biopsy samples. Suspect positive samples with HER-2 (++) were further examined by FISH. Consistence of HER-2 expression between resection samples and biopsy samples, and between resection samples from those patients undergoing neoadjuvant radiotherapy or radiochemotherapy and biopsy samples was analyzed. Association between HER-2 expression and clinicopathological characteristics was examined as well.
Results: Among 544 surgical resection samples, positive HER-2 samples of 20 cases (3.7%) were identified either by immunohistochemistry (HER-2, +++) or by FISH amplification. Among 235 paired biopsy samples, positive HER-2 samples of 5 cases (2.1%) were identified. Consistence of HER-2 expression between these two samples was 99.6% (234/235). The kappa value of consistence test was 0.907 (P<0.01). Consistence between resection samples from patients receiving neoadjuvant therapy and biopsy samples was 98.6% (73/74). There was no association of HER-2 over-expression or amplification with gender, age, tumor differentiation grade, lymph-node metastasis, distant metastasis, TNM stage and overall survival.
Conclusions: Positive rate of HER-2 expression is quite low in rectal cancer and has no relation to clinicopathological characteristics and prognosis. HER-2 status in biopsy samples of rectal cancer is highly consistent with paired surgical resection samples, which is not affected by neoadjuvant radiochemotherapy.