EP464 - Anastomotic Recurrence After Complete Pathologic Response to Neoadjuvant Chemoradiation

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Purpose/Background: Recent advances in pre-operative chemo radiotherapy have led to changes in the paradigm for treatment of locally advanced rectal cancer such as the transition from neoadjuvant chemoradiation and adjuvant chemotherapy to total neoadjuvant chemotherapy including full chemotherapy regimen followed by chemoradiation (Sauer, 2004). Novel treatment strategies have led to increase in complete pathologic response following neoadjuvant chemoradiation (Cercek, 2018).

Methods/Interventions: 60 year old male presented with rectal cancer diagnosed during a routine screening colonoscopy. His pathology was consistent with adenocarcinoma with mucinous features. Further staging workup with Pelvis MRI and CT of the chest abdomen and pelvis revealed T2N1disease without any evidence of distant metastasis. He was treated with neoadjuvant chemoradiation with 6 cycles of FOLFOX followed by Xeloda and radiation therapy 45 Gy over 25 Fx to the pelvis and 6 Gy over 3 Fx to the rectum. 3 cycles of FOLFOX were administered following radiation therapy. Post treatment sigmoidoscopy revealed a mass with mucosal abnormality 2cm from the anus. He underwent an ultralow anterior resection with sphincter sparing using Turnbull-Cutait technique and diverting loop ileostomy. 3 days later he was brought back to operating room and recto-anal anastomosis was performed. His hospital course was uncomplicated. His final pathology revealed pT0N0, with no residual disease and pathologic complete response.

Results/Outcomes: Subsequent sigmoidoscopy 4 months later showed a patent and circumferentially healed end-to-end colo-anal anastomosis. Following this, he underwent ileostomy reversal with a post-operative course notable for persistent diarrhea and mild fecal incontinence. 3 months after ileostomy reversal, 7 months after initial surgery, he presented with pelvic sepsis CT showed pelvic fluid collection concerning for anastomotic leak. He underwent percutaneous drainage and fecal diversion with diverting loop ileostomy. Following complete resolution of the pelvic collection, given his complete pathological response, he underwent a few hyperbaric oxygen treatments to aid with pelvic healing. Eventually, after extensive counseling, he underwent a completion proctectomy with end colostomy creation. His final pathology revealed pT2No rectal adenocarcinoma.

Conclusion/Discussion: When making the decision regarding of adjuvant therapy, one must always weight the benefit of subsequent therapy with the potential risk. In the setting of pathologic complete response, the use of adjuvant therapy remains a topic of debate. Multiple retrospective cohort studies have studied the benefit of adjuvant chemotherapy after neoadjuvant chemoradiation in the setting of pathologic complete response. Multicenter retrospective cohorts have shown improved overall survival in patients receiving adjuvant chemotherapy (Lai, 2023). Meta analyses of retrospective data has shown a similar benefit to adjuvant therapy in the setting of pathologic complete response (Dossa, 2018; Ma, 2019; Baloyiannis 2021). Despite encouraging retrospective results, no prospective data regarding adjuvant therapy after complete pathologic response is currently available.