Feasibility Study to Develop Sentinel Lymph Node Mapping in Rectal Cancer Patients

The purpose of this study is to see if investigators can develop a technique to identify sentinel lymph nodes in the rectum for rectal cancer patients with the use of a radiotracer (Tc-sulfur colloid), a dye (Spot), and imaging, both pre- and intraoperatively. Eligible patients are those with stage I-III rectal cancer undergoing standard low anterior resection or abdominoperineal resection. Investigators hypothesize that use of a unique intraoperative lymphatic mapping technique using a mobile gamma camera will identify the sentinel lymph node in patients with rectal cancer with greater than 80% sensitivity. Subjects will receive injections of the tracer and dye prior to surgery, have preoperative SPECT/CT imaging to be used as a guide to the rectal lymphatic system and then proceed to their scheduled surgery. During surgery, images of the rectum will be taken with a unique mobile gamma camera prior to removal and upon resection. If surgeons are able to identify the sentinel lymph nodes surrounding the rectal tumor, the hope is to combine this technique with a less invasive surgery called transanal endoscopic microsurgery (TEM) for early stage rectal cancer patients.

Subjects will have a preoperative flexible sigmoidoscopy where they will receive an endoscopic injection of 99mTc-sulfur colloid (up to 0.5 mCi) and 3 to 5 cc of circumferential endoscopic injections of Spot. A SPECT/CT will be performed prior to surgery to identify lymph nodes in the rectum. Subjects will proceed to their standard surgery. Intraoperative mobile gamma camera imaging of the rectum will occur before and after resection in attempt to identify sentinel lymph nodes.

Intraoperative images will be taken with a unique mobile gamma camera to identify sentinel lymph nodes in the rectum.

Evaluating the sensitivity of identifying the sentinel lymph node using a unique mobile gamma camera intraoperatively.

The primary endpoint is the sensitivity of sentinel lymph node (SLN) detection by the technique which will be estimated by the number of SLNs detected by the technique divided by the number noted at surgery or on final pathology review. 90% confidences interval around the estimate will help guide interpretation of the results.

Descriptive summaries will be used to list any complications that may have occurred pre-, intra- or post-operatively. Frequency and location of the sentinel lymph node (SLN) with respect to the tumor prior to surgery will be noted. In addition the location of the SLN in relation to the tumor will be documented during pathologic examination with the pathologist and surgeon to assess the feasibility of excision with transanal endoscopic microsurgery.

Inclusion Criteria: Adult patients with stage I,II, or III rectal cancer undergoing standard trans- abdominal low anterior resection or abdominoperineal resection surgery at the University of Virginia Willing and able to give written informed consent Exclusion Criteria: Patients less than 18 years of age Women who are pregnant and/or breastfeeding Prisoners Unable to give written informed consent Participants with medical contradictions or have potential problems complying with the requirements of the protocol, in the opinion of the investigator