V3 - The Endoscopic Spectrum Following Total Neoadjuvant Therapy for Rectal Cancer

Purpose/Background: The observation of complete tumor regression following neoadjuvant chemoradiation has led to organ preservation strategies. A Watch and Wait approach has been taken in select patients with complete clinical response, defined as, the absence of residue tumor clinically, endoscopically, and radiographically. Endoscopic findings of a complete clinical response include a flat white scar, telangiectasias in the absence of mucosal ulceration or nodularity. Residual nodularity with superficial ulceration or erythema is defined as a near complete response while visible tumor is an incomplete response. Despite these definitions, it may be challenging to distinguish between mucosal healing and residual disease.

Methods/Interventions: We sought to demonstrate the endoscopic findings of a complete clinical response, near complete response, and an incomplete response in patients undergoing endoscopy following completion of total neoadjuvant therapy for rectal cancer. We sought to demonstrate the subtle differences observed among patients with a complete clinical response with direct comparison of those without a complete response.

Results/Outcomes: Using prerecorded videos of flexible sigmoidoscopies, we show 14 video clips ranging from a complete clinical response to incomplete response. The first 11 videos demonstrate a complete clinical response. The classic description of a complete response is illustrated: a central white scar, telangiectasias without evidence of stenosis, mucosal irregularity, erythema, or ulceration. Subtle variations of a complete response are demonstrated. At times, the post treatment changes may be so subtle that it is difficult to locate the site of the prior tumor. On the contrary, a more pronounced central scar may be present causing a deformity. This can be devoid of mucosal centrally and give the appearance of pseudopoylpoid tissue formation from the leading edge of normal mucosa. Initially, this may be thought to represent mucosal irregularity, but is actually normal mucosa sitting across the scar giving this appearance. We demonstrate the importance of comparing the stability in endoscopic findings at different time durations. In contrast, a near complete response is shown, demonstrating the mucosal irregularity that differs in appearance from the surrounding mucosa in coloration and nodularity representing residual tumor. Finally, the incomplete response shows residual tumor and luminal stenosis that precludes adequate visualization of the mucosa.

Conclusion/Discussion: The endoscopy findings following a complete clinical response after total neoadjuvant treatment for rectal cancer should demonstrate the lack of residual mucosal irregularity or ulceration, pale white scar, with or without telangiectasias. Pseudopolypoid tissue may be present. The use of endoscopic videos allows for 3-dimensional comparison to ensure stability of the scar.