OBJECTIVETo investigate the correlation of expression of vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (Ki67) with sensitivity to neoadjuvant chemoradiation in rectal adenocarcinoma.

METHODSSamples of pretreatment biopsies and the resected specimens after neoadjuvant therapy in 32 patients with rectal adenocarcinoma were collected, and the expression of Ki67 and VEGF were detected by immunohistochemistry using specific antibodies. The correlation of Ki67 and VEGF expression with clinicopathological factors were analyzed.

RESULTSThe level of VEGF expression was significantly correlated with lymph node metastasis (P = 0.033), depth of tumor invasion (P = 0.007) and TNM stage (P = 0.016), but not with histological type, tumor size, age and gender of the patients (P > 0.05). However, VEGF expression was found to be negatively and significantly correlated with the sensitivity to neoadjuvant chemoradiation (P = 0.016), and a transient increase of VEGF expression was detected in the resected specimens after neoadjuvant therapy (P = 0.035). Ki67 labeling index (Ki67-LI) was found to be significantly correlated with lymph node metastasis (P = 0.028), but not with tumor size, age and gender of the patients (P > 0.05). It was also found that tumors with lower Ki67-LI expression were more sensitive to neoadjuvant therapy than that with higher expression of Ki67-LI (P = 0.032). In contrast with VEGF, the Ki67 expression level decreased after neoadjuvant therapy, but no statistical significance was found between pretreatment and posttreatment specimens (P > 0.05).

CONCLUSIONThe preliminary results of this study demonstrate that the expression of VEGF and Ki67 in pretreatment biopsy of rectal adenocarcinoma may be used as a biomarker to predict tumor response to neoadjuvant chemoradiation.