Objective   To identify the ABCG2 expression levels in colorectal cancer patients and its relationship with clinicopathological features and the efficacy of irinotecan-based chemotherapy and to provide further theoretical basis for individualized treatment.

  Methods   Clinical data and tumor samples from patients with metastatic CRC who have received irinotecan-based chemotherapy at the Department of Gastroenterological Oncology, Peking University Cancer Hospital from January 1996 to December 2011 were collected. The immunohistochemical method was used to detect ABCG2 expression levels both in colorectal carcinoma and tumor-adjacent normal tissues. The correlations of the expression of ABCG2 with clinicopathological features and the efficacy of irinotecan-based chemotherapy were statistically analyzed.

  Results   1) Immunohistochemical staining shows that the positive rate of ABCG2 expression in the colorectal cancer samples is 93.2%, which is significantly higher than that in normal colon mucosa at 43.6% (P < 0.05). No significant associations were observed between ABCG2 expression and age, gender, tumor differentiation, primary tumor sites, or liver metastasis.(2) ABCG2 expression has no significant correlation with the efficacy of irinotecan-based chemotherapy (P>0.05).

  Conclusion   ABCG2 expression has no significant correlation with the efficacy of irinotecan chemotherapy in patients with colorectal cancer.