Feasibility study of a Response Surveillance Program in locally advanced mid and low rectal cancer to increase organ preservation.

BACKGROUND

Assessment of tumor response in rectal cancer after neoadjuvant treatment by MRI (Tumour Regression Grade, TRG 1-5) is well standardized. The overall timing and method of defining complete response (cCR) remain controversial. The aim of this work was to evaluate the feasibility of a defined Response Surveillance Program (RSP) to increase organ preservation for locally advanced rectal cancer after neoadjuvant treatment.

METHODS

A standardized program of clinical (CR), radiological (RR) and metabolic (MR) assessment of tumor response is defined over a 6 month period from completion of NACRT with formal assessment performed every 2 months (M). Patients with TRG1-3 at M2 and TRG1-2 at M4 continue in the program up to M6 assessment. Patients managed with this protocol from 2016 to 2020 were analyzed. The primary endpoint was rectal preservation rate. Secondary endpoints included disease-free survival and overall survival at 3 years.

RESULT: 314 potentially suitable patients were enrolled in the RSP and 50 patients completed the six month program and were successfully enrolled into watch and wait. Fourteen (28%) were T2 tumor stage, 27 (54%) T3 and nine (18%) were T4. During watch and wait, patients with locoregional recurrence (n = 11) were treated with local excision (n = 3), endocavitary radiotherapy (n = 1), TME (n = 5) and APR (n = 2). With a median follow-up of 32 months, the rectal preservation rate was 88%, with a 3-year disease-free survival of 67% and an overall survival of 98%.

CONCLUSION

This study validates the feasibility of the practical implementation of a Response Surveillance Program to increase organ preservation rates without compromising oncological outcomes in rectal cancer.