eP212 - Using Indocyanine Green for Localization of Rectal Tumor in Low Anterior Resection

Purpose/Background: Laparoscopic and robotic platforms allow surgeons to perform minimally invasive surgery (MIS) rectal cancer resections. Intraoperative identification of rectal neoplasms can be challenging. Accurate identification of tumor sites optimizes oncological resection. In the past, Delphi Consensus has provided appropriate documentation, indications, location, and method of tattoo placement, to standardize marking of rectal tumors. However, tattoos of the mid to low rectum can be difficult to visualize as well as cause fibrosis and potentially altering dissection planes. Recent literature has advocated the use of indocyanine green (ICG) for tumor localization. In this case study we highlight the administration of ICG via intraoperative sigmoidoscopy for localization of rectal cancer during robotic low anterior resection (LAR).Methods/Interventions: 57-year-old woman who presented with rectal cancer detected on screening colonoscopy. Staging MRI showed 6cm T3N2b invasive adenocarcinoma of the rectum at 7 cm. CT chest, abdomen and pelvis confirmed no metastasis.

70-year-old man who presented with rectal cancer detected on screening colonoscopy. Staging endoscopic ultrasound showed 3cm T3N0 invasive adenocarcinoma of the rectum at 1cm. CT chest, abdomen and pelvis confirmed no metastasis.

Both patients underwent neoadjuvant chemoradiation with long-course radiation followed with 6 months of FOLFOX chemotherapy treatment.Results/Outcomes: Upon re-staging they had near-complete response to neoadjuvant treatment. The first patient was found to have low-grade dysplasia on repeat endoscopy of the rectal scar. The second patient’s biopsy showed hyperplastic changes with no evidence of dysplasia or malignancy on repeat endoscopy; however, MRI of the pelvis showed a residual rectal mass. Both patients underwent LAR. At the start of surgery, both patients had 0.1 mL (ICG dose: 0.5 mg) injected in all four quadrants approximately 2 cm distal to the tumor using flexible sigmoidoscopy. Final pathology showed >10 lymph node harvest with negative circumferential margin and distal resection margin of 2 cm for both patients.Conclusion/

Discussion: ICG has been used in medical applications since the mid-1950s and was originally employed for quantitative measurement of hepatic and cardiac function. Satoyoshi et al., found that ICG can be reliably used for localization of colorectal tumors if ICG is injected into the submucosal layer around the tumor within 6 days of surgery. The use of ICG has enhanced the total number of harvested lateral pelvic lymph nodes without impairing functional preservation in complex laparoscopic lateral pelvic lymph node dissection when compared to non-ICG groups (14 versus 9). In the past, studies have used ICG angiography to localize rectal cancer, assess the viability of the rectal stump and proximal colon prior to anastomosis, and identify dentate line or anal margin during complex LAR. However, there is a lack of guidelines and protocolization for ICG use in colorectal surgery. With the growing use of MIS, the use of ICG for intra-operative localization of low rectal cancers provides a valuable tool for oncological resection.ICG marking of rectal cancerFour quadrant ICG markings 2 cm distal to the rectal cancer using flexible sigmoidoscopy