eP201 - Diverticular Stricture Complicating the Watch and Wait Approach to Rectal Cancer

Purpose/Background: The management of locally advanced rectal cancer has evolved to include the Watch and Wait strategy for patients with complete clinical response (CCR) after neoadjuvant chemoradiotherapy. Unfortunately, these patients are still susceptible to other colorectal pathologies, which complicates the management of rectal cancer in Watch and Wait patients. There are no case reports or guidelines regarding the surgical management of patients who present with an adjacent colorectal pathology to the previously treated rectal cancer. This is a case of a 79-year-old female who presented with a sigmoid colon diverticular stricture two years after initiation of Watch and Wait management for a mid-rectal cancer.Methods/Interventions: A 79-year-old female was diagnosed with a moderately differentiated rectal adenocarcinoma with normal mismatch repair status after colonoscopy. She had a rectal MRI, showing a mid-rectal T3N0 lesion. The patient underwent total neoadjuvant therapy (TNT) consisting of 8 cycles of FOLFOX, followed by cepecitabine-sensitized radiotherapy. On three-month surveillance, there was no palpable abnormality on digital rectal exam, endoscopy showed a benign scar, and rectal MRI confirmed complete regression of the mid-rectal cancer. The patient was managed with Watch and Wait which included regular physical exams, endoscopy, serum CEA, rectal MRI, and CT chest/abdomen/pelvis per NCCN guidelines.The patient began experiencing obstructive symptoms two years after initiation of Watch and Wait management, prompting a colonoscopy which showed a near complete, diverticular sigmoid stricture. Virtual colonography showed a 2 cm long stricture of the distal sigmoid within a cluster of diverticula. MRI and CT chest/abdomen/pelvis showed no locoregional or distal recurrence of prior rectal cancer. A shared decision was made with medical and radiation oncology to proceed with sigmoid colectomy, without rectal resection.Results/Outcomes: The patient underwent a laparoscopic sigmoid colectomy with primary anastomosis to the upper rectum. Operative findings demonstrated a fibrotic sigmoid colon with no evidence of rectal cancer. Pathology revealed macroscopic and microscopic findings of a diverticular stricture. The patient was discharged on postoperative day two and continued to do well on follow up.Conclusion/

Discussion: The recurrence rate of rectal cancer in patients managed with the Watch and Wait method is approximately 15-28%. Assessing the likelihood of recurrence helps surgeons plan whether to include the prior rectal cancer site in the resection or leave the rectum in situ. Factors that influence the extent of the colorectal resection should include review of prior rectal tumor biology, initial CEA level and TNM staging, length of complete clinical remission greater or less than 2 years, as well a pre-operative screening for locoregional recurrence. Pre-operative screening should include repeat CEA, endoscopy, CT chest/abdomen/pelvis, and rectal MRI. Additionally, there may be a role for ctDNA in detecting early recurrence. As more patients undergo a Watch and Wait approach, hopefully more data will emerge to clarify management of this complex clinical scenario.