The predictive value of vascular endothelial growth factor and Ki-67 expression on neoadjuvant therapy in rectal cancer

Objective To investigate the expressions of vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (Ki-67) in patients with rectal adenocarcinoma and their associations with neoadjuvant therapy. Methods The expressions of Ki-67 and VEGF in 32 cases of rectal adenocarcinoma, including both pretreatment tumor biopsies and postoperative specimen, were detected by immunohistochemistry using specific antibodies, and were correlated with clinicopathological factors. Results The intensity of VEGF staining was significantly correlated with lymph nodal metastasis ( P = 0.033), depth of tumor invasion ( P = 0.007) and tumor stage ( P = 0.016), but not with histological types, tumor sizes, patients’ ages and genders ( P > 0.05). Low level of VEGF expression had significant correlation with the high sensitivity of response to neoadjuvant therapy ( P = 0.016). The transient increase of VEGF expression could be seen after neoadjuvant therapy ( P = 0.035). Ki-67 labeling index (Ki-67-LI) was significantly correlated with lymph node metastasis ( P = 0.028), but not correlated to tumor sizes, patients’ ages and genders ( P > 0.05). Tumors with lower Ki-67-LI were more sensitive to neoadjuvant therapy ( P = 0.032). The Ki-67 level decreased after neoadjuvant therapy, but no statistical significance was found ( P > 0.05). Conclusion Our results demonstrate that the expression of VEGF and Ki-67 in pretreatment rectal adenocarcinoma biopsies may be predictive of tumor response to neoadjuvant therapy.