Epidermal growth factor receptor overexpression and the tumor response to preoperative radiochemotherapy for patients with advanced rectal cancer

Background : An association between the epidermal growth factor receptor (EGFR) signaling pathway and the response of cancer cells to ionizing radiation has been previously described. Preoperative radiochemotherapy (PRCT) has been administered for treating locally advanced rectal cancer to improve the outcomes, and to preserve the sphincter from low-lying tumor. However, the responses of tumors to PRCT are variable and there are currently no reliable markers that predict the therapeutic benefits. We studied the association between EGFR overexpression and the tumor response to PRCT in rectal cancer. Methods : The EGFR protein expression, as determined by immunohistochemistry, was analyzed in the pretreatment biopsy specimens from 120 patients with advanced rectal cancer. The tumor response was graded in the surgically resected specimens by using a three-scale grading system: no response (NR), partial remission (PR) and complete remission (CR). Results NR was identified in 70 cases (58.3%). Fifty patients (41.7%) responded to PRCT; 27 (22.5%) achieved a PR and 23 (19.2%) achieved a CR. EGFR overexpression was detected in 78 (65%) cases. Seventy-eight percent (39/50) of the tumors with a CR/PR revealed EGFR reactivity, whereas 55.7% (39/70) of the tumors with NR showed an EGFR expression (p=0.048). Conclusions : The EGFR protein expression might be a valuable marker for identifying those patients who are most likely to benefit from PRCT.