Wait and Watch Approach for Patients With Rectal Cancer Following Neoadjuvant Therapy.

Purpose/Objective(s) Wait-and-watch (W&W) approach for select rectal cancer patients is gaining popularity due to the detrimental effects of surgery on patient's quality-of-life. Here, we present the oncological outcomes of patients managed by W&W approach in a large cancer center network. Materials/Methods Patients with rectal cancer who underwent neoadjuvant therapy (NAT), and had clinical complete or near complete response (cCR) were managed by W&W approach. Disease evaluation was by clinical examination, imaging, and endoscopy. Baseline characteristics including age, gender, tumor location, use of MRI for staging, maximum tumor size and stage, along with time to start and duration of NAT were examined. Kaplan-Meier estimates were used to assess local regrowth (LR), disease-free survival (DFS), and overall survival (OS). Univariate and multivariate Cox models were used to identify factors associated with LR and DFS. Results Between 2010 and 2020, 1400 patients were referred for NAT. Of these, 96 patients (6.85%) were managed by W&W approach. There was a progressive increase in the adoption of W&W. Among the current W&W cohort (N = 96), only 1 patient (1.5%) was diagnosed in 2010, whereas 21.8% and 26% of the cohort were diagnosed recently in 2018 and 2019, respectively. Median follow-up was 23 months (IQR 11,36). Median age was 65 years (IQR 57,73). 21% of the cohort were 75 years or older. Majority of the patients had MRI for staging (76%) and were noted to have low rectal tumors (65.6%). Most of the patients had T3 tumors (62.5%) and were node negative (57.4%). Long course chemoradiation (CRT) followed by 4 months of chemotherapy (41.6%) was the commonest NAT approach, while the other approaches included chemotherapy followed by CRT (25%) or CRT alone (25%). At the start of this program, few patients (16.6%) underwent trans anal excision to confirm pathological complete response. Isolated local regrowth (LR) was noted in eight patients (8.3%), and distant relapse (DR) in 3 patients (4.34%). Salvage surgery was performed in 7 LR patients, while one patient refused surgical intervention. At 1-year, LR rate was 4.7%, DFS was 92.9%, and OS was 98.7%. Similarly, at 3-years, LR rate was 11.5%, DFS was 81.7%, and OS was 92.1%. Importantly, response on MRI did not correlate with either endoscopic assessment of disease status (P > 0.99) or local regrowth (P > 0.99). Finally, tumor size within the highest tertile (> 50mm) was associated with worse LR (81.3% vs. 92.3%, P = 0.04) and DFS (73.9% vs. 85.7%, P = 0.025). In a multivariable Cox model, tumor size within the highest tertile was associated with both LR (HR 8.4, 95% CI 1.5-45.8, P = 0.01) and poor DFS (HR 5.6, 95% CI 1.4-22.0, P = 0.01) independent of age, tumor location, MRI usage, and time to start and duration of NAT. Conclusion Our data supports the use of W&W approach following NAT for select rectal patients with a clinical (near) complete response given the excellent short-term outcomes. The impact of tumor size on local regrowth and DFS should be confirmed in a prospective study.