In patients meeting eligibility requirements outlined below, comparisons will be made between direct pO2 measurements using a tissue hypoximeter and IHC-assessed expression of hypoxia related proteins (HIF-1α, VEGF, CA IX and GLUT-1) in both normal and tumor tissue.

Patients consented to the protocol will proceed to their surgery date without any change in the standard preoperative period. After arriving in the operating room, the patient will undergo intravenous general anesthesia (or spinal/epidural anesthesia) by the anesthesiologist and will receive 40% oxygen. At this time, the principal investigator (along with the assistance of the operating surgeon and a member of the Department of Medical Physics) will use the Eppendorf hypoximeter to gather pO2 measurements. We anticipate that this will add no more than fifteen minutes to the planned procedure. Once the measurements are collected, the anesthesia will be adjusted as appropriate for the surgery and the procedure will continue as usual.

Measure pO2 in rectal cancers

with direct tumor hypoximetry in tumor and normal tissue.