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.