Predictive value of Smac, VEGF and Ki-67 in rectal cancer treated with neoadjuvant therapy.

The present study aimed to identify whether second mitochondria-derived activator of caspase (Smac), vascular endothelial growth factor (VEGF) and proliferating cell nuclear antigen (Ki-67) expression in pre-treatment tumor biopsies are useful predictive markers of tumor response in patients with rectal cancel undergoing pre-operative chemoradiotherapy (CRT) Paraffin-embedded tissues obtained before and after therapy were evaluated by immunohistochemical staining for Smac, VEGF and Ki-67 The study evaluated the correlation of Smac, VEGF and Ki-67 immunoreactivity in tumor biopsies before treatment of tumor response to pre-operative CRT Regarding Smac, patients with a favorable response to neoadjuvant CRT had higher pre-therapy levels (p=0 011) The level of Smac expression decreased after neoadjuvant therapy (p=0 044) However, VEGF expression was found to be negatively and significantly correlated with a favorable tumor response to neoadjuvant CRT (p=0 010) A transient increase in VEGF expression was detected in the resected specimens following neoadjuvant therapy (p=0 030) In addition, tumors with a low Ki-67 labeling index (Ki-67-LI) expression were found to be more sensitive to neoadjuvant therapy than those with a high expression of Ki-67-LI (p=0 034) In contrast to VEGF, the Ki-67 expression level decreased after neoadjuvant therapy Smac VEGF and Ki-67 expression levels assessed immunohistochemically from pre-treatment tumor biopsies, may be useful predictive markers of rectal tumor response to pre-operative CRT