VM36 - Post-Total Neoadjuvant Therapy Dilemmas: Navigating Decision-Making with Near Complete Response

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Purpose/Background: Of patients with locally advanced rectal cancer, approximately 45-55% achieve a clinical complete response following total neoadjuvant therapy (TNT), potentially avoiding the need for surgical intervention. This possibility allows many patients to avoid the morbidity associated with proctectomy, including urogenital and bowel dysfunction, and possibly a permanent stoma. However often the decision-making process is unclear for patients that achieve a near complete response and can be heavily influenced by informed risk discussions with patients.

Methods/Interventions: This case discusses a 49-year-old male with locally advanced mid-rectal cancer who underwent total neoadjuvant therapy for T3N1 mid-rectal lesion. Restaging following completion of TNT, endoscopic evaluation revealed a small nodular area consistent with a near complete response with pelvic magnetic resonance imaging (MRI) suggesting complete response. He continued under close surveillance with repeat assessments over a period of 6 months for a near complete response. After that time, he was recommended to undergo low anterior resection with total mesorectal excision (TME) due to persistence of the nodular lesion but declined due to the desire to avoid potential morbidity of proctectomy. Alternate strategies were discussed, and he ultimately elected to have robotic transanal excision rather than TME.

Results/Outcomes: See video. Pathology revealed a full thickness specimen containing tubulovillous adenoma with high-grade dysplasia, surrounded by scar tissue, and negative margins.

Conclusion/Discussion: This case highlights the ongoing challenges of determining a complete clinical response after TNT and the associated management decisions. TME is traditionally considered the gold standard for curative resection and current guidelines from the American Society of Colorectal Surgeon’s and the National Comprehensive Cancer Network’s guidelines do not include local excision within treatment algorithms after TNT. The OPRA trial reports up to 8.6% of patients with near complete response following TNT were treated with local excision, despite the lack of clear guidelines for this approach in cases of near complete response or local recurrence. While data is limited following TNT, studies suggest less morbidity and comparable oncologic outcomes to TME following standard neoadjuvant chemoradation therapy in select patient populations. This case underscores the potential of TNT to downstage tumors and facilitate organ-preserving approaches like transanal excision in select patients with concern for persistent local disease. Further literature is warranted to better define the criteria for patient selection and to compare long-term outcomes between local excision and TME in the context of TNT. This is of particular importance as the ongoing evolution of treatment strategies for rectal cancer emphasizes the importance of individualized patient care, balancing oncological safety with quality-of-life considerations.