Lymphatic Mapping for Sentinel Node Identification and Analysis

The main objective of this study is to determine whether the first (sentinel) lymph nodes in the drainage pathway of colonic tumour can be detected at the time of surgery using a new technique. The detection method is to inject a fluorescent dye (indocyanine green) adjacent to the tumour. The dye will then be seen as it fluoresces in the light form the near infrared spectrum that can be used at the time of the laparoscopic (keyhole) surgery. An endoscope is placed in the colon (colonoscopy) during surgery and the tracer fluorescent agent is injected around the tumour. The mesentery in which the lymph nodes draining the tumour are located will then be examined by laparoscopy as it is expected that fluorescence will be identified within approximately 5 minutes of the injection. The first lymph node or nodes that take up the fluorescent dye will then be marked by placing a clip or a stitch by them. After the surgery has been completed and colon removed all lymph nodes can be examined microscopically by the pathologist, paying a particular attention to whether any tumour cells are present in the sentinel lymph nodes and whether the presence or the absence of tumour cells in that node accurately reflects the tumour status of the rest of the specimen.

If this pilot demonstrates that sentinel lymph nodes can be reliably detected, we have developed a technique which allows us to remove a small area (less than 5 cm) of the colon. Using this procedure should decrease complications following traditional surgery. We however also need a method that allows accurate assessment of the lymph nodes draining the tumour. This pilot trial will examine our ability to detect such 'sentinel' lymph nodes so that we can use their status (positive for cancer cells or negative) to determine whether a smaller operation such as full thickness localised excision is adequate treatment for the patient and that they can avoid a larger operation.