Sentinel Lymph Node Mapping in Rectal Cancer

The purpose of this study is to develop a technique that allows physicians to identify the first lymph nodes draining from a rectal tumor (the sentinel lymph nodes). Currently, there is no technique used to find these lymph nodes in the rectum during surgery and therefore many patients with rectal cancer need to undergo a total rectal resection. Dyes, tracers, imaging and a gamma probe will be used in this study during a standard minimally invasive transanal endoscopic surgery (TES) to try to locate these lymph nodes. If surgeons are able to locate these lymph nodes they will be removed during surgery. If the technique is successfully developed as a result of this research, it could help patients in the future with early stage rectal cancer by allowing doctors to see if their cancer has spread to the lymph nodes of the rectum without having to undergo a total rectal resection. These patients would then be able to undergo a TES combined with a lymph node dissection to gain more knowledge about the stage of their disease. This knowledge would then be used to determine if and what further treatment is necessary for the patient's rectal cancer.

Subjects will come to the OR and undergo a flexible sigmoidoscopy after induction of anesthesia and receive separate endoscopic injections of Spot (up to 5 cc), 99mTc-sulfur colloid (up to 0.5 mCi), and Indocyanine green (ICG) (1 ml). Patient will undergo the standard transanal endoscopic surgery (TES) to remove the rectal neoplasm, exposing the lymph node basin. The sentinel node(s) will be identified using a combination of the gamma probe and fluorescence imaging endoscopically, dissected out, and removed through a transanal approach.

Endoscopic near infrared (NIR) imaging of ICG and detection of radiotracer with gamma probe after standard removal of rectal neoplasm.

Data from the first 6 eligible patients will be used to verify feasibility. For this phase, the data need to support a detection rate of at least 50% for the procedure to be considered feasible to move forward with the 2nd phase. The proposed SLNm technique will be declared 'feasible' if at least one SLN is identified per patient. Identification of the SLN in three consecutive patients would provide 80% confidence of successful identification more than 50% of the time. A total sample of size of 6 patients would allow for three refinements in technique if necessary to establish feasibility.

2nd Phase: Sample size is set at 16 eligible patients. For this study, continued investigation of the proposed technique would be of interest if 70-100% of the SLNs are detected. If at least on SLN is detected in 14 of 16 patients, an observed rate of 87.5%, then the lower limit of a one-sided 90% confidence interval is 70%. Thus, detection of at least one SLN in 14 or more patients out of 16 assessed would provide strong preliminary data for the technique (i.e. SLN is detected in at least 70% of patients). If it's assumed, on average, 1.5 SLN could be identified and excised per patient, then with 24 possible SLN, the estimated rate of SLN positive for disease would have an expected half width (or precision of the estimate) of 12-14%.

Inclusion Criteria: Adult patients undergoing elective transanal endoscopic surgery (TES) at the University of Virginia for rectal neoplasm (polyp with high grade dysplasia, T1N0 tumors < 3cm in the absence of poor pathologic features, patients that refuse radical resection) 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 Patients with any of the following: Allergy to technetium, Spot and/or ICG Allergy to iodides Severe cardiac disease (hospitalization for cardiac disease in the last year, congestive heart failure, abnormal EKG) or renal disease (Creatinine > 2.0 mg/dL) Patients with medical contradictions or have potential problems complying with the requirements of the protocol, in the opinion of the investigator