EP828 - The Hurdles in Wait and Watch Protocol of Rectal Cancer following Total Neoadjuvant Therapy: A Single Centre Experience

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Purpose/Background: The advent of total neoadjuvant therapy (TNT) in high risk locally advanced rectal cancer has doubled the rate of pathologic complete responders(pCR) .This attractive rate of pCR has opened the door for the " Wait and Watch" protocol. A number of questions related to TNT remain currently unresolved including the indications, preferred radiotherapy and chemotherapy regimens, their sequence and the timing of surgery.In this study we outline our experience and the main hurdles we faced when employing the TNT strategy for Wait and Watch protocol.

Methods/Interventions: We did a prospective analysis of our rectal cancer database from May 2020 to June 2024.All patients of locally advanced high risk rectal cancer who consented for intentional Wait and Watch and surveillance were administered Short course Radiotherapy - (5x 5 Gy) followed by chemotherapy - (FOLFOX X 9 cycles / CAPEOX X 6 cycles ).We performed an interim MRI at 8 to 10 weeks.All patients who had clinical progression on interim MRI were excluded from the study ( the patients underwent surgery as feasible).All other patients were reassessed with a Digital Rectal Examination (DRE) , MRI Pelvis and Rectoscopy at 2 weeks after completion of TNT.Our surveillance protocol for the patients on Wait and Watch protocol was a DRE , Rectoscopy and MRI pelvis every 2 months for the first 12 months, thereafter 4 to 6 monthly for 24 months. We performed a CT scan of the Thorax Abdomen and Pelvis yearly.

Results/Outcomes: The total number of patients included in the study was 94.The number of incomplete responders (iCR) , near complete responders (nCR) and complete clinical responders (cCR) was 47 (50%) ,12 (12.7 %) and 35 (37.2 %) respectively.In the 47 patients who were incomplete responders, 15 patients defaulted after chemotherapy.The surgical outcome of the incomplete responders were as follows: Abdominoperineal resection (APR) - 8 , Hartmanns procedure - 1 and Sphincter preserving surgeries - 21 .Two patients of the iCR group were managed with transanal excision (TAE) and were put on wait and watch protocol.One patient in the iCR group developed a local regrowth (post TAE ) and defaulted from further treatment. In the nCR group of 12 patients , 3 patients underwent APR and 9 patients underwent transanal excision.In the cCR group of 35 patients - 32 patients were on Wait and Watch (W and W) protocol.Three patients on W and W protocol developed local regrowths . Two of the three patients were salvaged by - transanal excision (1) and Ultra low anterior resection (1).One of the three patients defaulted from further treatment.The total number of defaulters in the study was 17 ( 20 %) and the majority of them were following chemotherapy.The number of patients who developed distant metastases was 5.The total number of patients who are continuing Wait and Watch protocol is 40 (42.5%.) The number of patients who developed local regrowths were 8 (17 %).The median follow up period of our study is 18 months.

Conclusion/Discussion: The intentional Wait and Watch protocol following total neoadjuvant therapy requires strict compliance from the patient and meticulous surveillance from the treating doctor.The study had a 20 % treatment default rate and a 36 % failure to reversal of stoma in our patients which is concerning .The cost factor of the imaging protocol also placed a financial burden on our profile of patients.The hurdles we faced in this study highlights the need for careful decision making in Wait and Watch protocol , especially in resource limited cancer centres.