The watch-and-wait strategy versus radical resection for rectal cancer patients with a good response (≤ycT2) after neoadjuvant chemoradiotherapy

PURPOSE: This study aims to oncologic outcomes of the watch-and-wait (WW) strategy compared with radical resection (RR). METHODS: Patients with rectal cancer who received neoadjuvant chemoradiotherapy (nCRT) and achieved ≤ycT2 between 2008 and 2016 were included. The mean follow-up time was 61 months (range, 0–168 months). Recurrence-free survival (RFS), local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS) were compared. A total of 446 patients were included, and WW was adopted for 34 patients. RESULTS: WW patients were older (P = 0.022) and less advanced initial cT stage (P = 0.004). Ten patients in the WW group (29.4%) experienced local regrowth. Later, distant metastases occurred in 7 of these patients. The 5-year RFS (74.1% vs. 79.5%), DMFS (74.1% vs. 81.6%), and OS (90.4% vs. 87.7%) for the WW and RR groups were not statistically different. However, LRFS in the WW group was significantly lower (65.1% vs. 97.0%, P < 0.001). The initial cT stage was associated with RFS (P = 0.019) and LRFS (P = 0.037). WW was an independent risk factor for LRFS (P < 0.001) and DMFS (P = 0.024). After 1:4 propensity score matching between the WW and RR groups, there was no difference in RFS and OS. However, the 5-year LRFS (67.5% vs. 96.5%) and DMFS (73.2% vs. 86.4%) demonstrated a statistically significant difference between the groups. CONCLUSION: By appointing the WW strategy, oncologic safety was not ensured. The WW strategy must be implemented with caution in patients with ≤ycT2 stage, particularly those with advanced initial cT stage.