NON-OPERATIVE MANAGEMENT WITH A WATCH AND WAIT PROTOCOL IN RECTAL CANCER: A SINGLE-CENTER RETROSPECTIVE ANALYSIS OF CLINICAL OUTCOMES AND THE IMPACT OF MAGNETIC RESONANCE IMAGING

Introduction: The non-operative rectal cancer approach, through watch and wait (WW) protocol, has increasingly been accepted as an option for patients who achieve a complete or near-complete clinical response after neoadjuvant therapy. Nonetheless, the recurrence rates reported in several retrospective trials and, recently, prospective trials have varied substantially. Objective: We aimed to retrospectively access clinical outcomes in patients with rectal cancer who underwent a non-operative approach and WW protocol in our Institute. In addition, we sought to evaluate whether certain parameters of pre and post neoadjuvant magnetic resonance imaging (MRI) correlate with recurrence and survival. Methods: We included pts with a non-metastatic rectal cancer at diagnosis, from 2011 to 2020, who achieved a complete or near-complete clinical response after neoadjuvant therapy. All patients included had the responses evaluated through proctologic clinical examinations, in addition to radiologic evaluation through computerized tomography scans (CT) with or without a pelvic MRI. For patients who underwent an MRI, pre-neoadjuvant reports were accessed to obtain baseline tumor and lymph-node staging, in addition to extramural vascular invasion status (positive or negative). We analyzed post-neoadjuvant MRI reports to obtain any residual lymph-node status (positive or negative). Local and distant recurrence rates, colostomy rates, and survival were evaluated as clinical outcomes at each patient’s final follow-up. Results: Among 34 patients included for analysis, 8 (23%) required a colostomy, 17 (50%) developed a local recurrence, 13 (38%) developed a metastatic recurrence, 13 (38%) died from rectal cancer, and 10 (29%) are free from recurrence within a mean follow up of 44 months. We did not find a statistically significant association between MRI features and recurrence or death. Still, we could find that among the ten patients (29%) who had a CT instead of an MRI as the post-neoadjuvant response imaging evaluation, distant recurrence rates were significantly higher (p=0.026). Conclusion: In our cohort, even though non-operative and WW management were associated with a long-term lack of recurrence for a proportion of patients, distant recurrences were frequent and significantly associated with the lack of MRI evaluation in the post-neoadjuvant setting.