The goal of this study is to determine if concepts established in mouse models of the tumor microvascular response to ionizing radiation (IR) therapy are applicable to human tumors in order to begin to establish that the engagement of the endothelial response is a valid target for IR in human tumors. A portion of tumor will be isolated from individuals who have signed informed consent for this protocol and are undergoing surgery on the Neurosurgery, Colorectal, and Gynecology, Head and Neck, Urology, and Hepatobiliary Services at Memorial Sloan-Kettering Cancer Center. Tumor tissue will be obtained from the surgical sample in pathology after adequate specimens have been obtained for diagnostic purposes. Tumor tissue will be irradiated ex vivo and the microvascular endothelial response will be determined. From specimens of adequate size, a pure tumor endothelial cell population will be isolated and the response to IR will be determined.