Angiogenic Marker Associated With Resistance To Neoadjuvant Chemoradiotherapy In Rectal Cancer

11030 Background: The ability to achieve pathologic down staging after neoadjuvant chemoradiotherapy (CRT) is correlated with improved survival. However, there is no effective method of predicting which patients will response to neoadjuvant CRT. Neoadjuvant CRT can change the expression of angiogenic factors. However, little is known about its possible changes in response to preoperative CRT. We examined the expression of angiogenic factors in rectal cancer tissues before preoperative CRT and after surgery. Methods: Fifty five patients with locally advanced rectal cancer were studied. All patients were given preoperative CRT of 5040 cGy for 5-6 weeks with concurrent administration of 5-fluorouracil and leucovorin. Surgical resection was performed 6–8 weeks later in all patients. Immunohistochemical staining for angiogenenic markers (vascular endothelial growth factor [VEGF], placenta growth factor [PLGF], hypoxia inducible factor 1α [HIF 1α], stromal cell derived factor [SDF 1α]) were performed on specime...