Despite the optimization of the local treatment of advanced rectal cancer (LARC), combination of preoperative chemoradiotherapy (CRT) and surgery, approximately one third of patients will develop distant metastases. Since the chemokine receptor CXCR4 has been implicated in metastasis development and prognosis in colorectal cancer, the role of the entire axis CXCR4-CXCL12-CXCR7 was evaluated to identify high relapse risk rectal cancer patients. Tumor specimens of 68 LARC patients undergoing surgery after neoadjuvant-CRT were evaluated for CXCR4, CXCR7, and CXCL12 expression through immunohistochemistry. Multivariable prognostic model was developed using classical prognostic factors along with chemokine receptor expression profiles. High CXCR4 correlated with a shorter relapse-free survival (RFS) (p= 0.0006) and cancer specific survival (CSS) (p= 0.0004). Concomitant high CXCR4-negative/low CXCR7 or high CXCR4-negative/low CXCL12 significantly impaired RFS (p= 0.0003 andp= 0.0043) and CSS (p= 0.0485 andp= 0.0026). High CXCR4/N+ identified the worst prognostic category for RFS (p< 0.0001) and CSS (p= 0.0003). The optimal multivariable predictive model for RFS was a five-variable model consisting of gender, pT stage, N status, CXCR4, and CXCR7 (AUC = 0.92, 95% CI = 0.77–0.98). The model is informative and supportive for adjuvant treatment and identifies CXCR4 as a new therapeutic target in rectal cancer.© 2013 UICCWhat's new?
Approximately one-third of patients with locally advanced rectal cancer (LARC) develop distant metastases. To gain further insight into LARC biology, the authors of the present study evaluated the chemokine axis CXCR4-CXCL12-CXCR7 in poor-responder, neoadjuvant treated LARC patients. Axis expression was found to be an extremely powerful tool for the identification of patients with high risk of relapse, who are also ideal subjects for adjuvant therapy. CXCR4 and CXCR7 specifically were two of five variables that constituted the optimal multivariable predictive model for relapse free survival. Moreover, the CXCR4-CXCL12-CXCR7 axis is a suitable therapeutic target.