National implementation of Watch-and-Wait in patients with rectal cancer

INTRODUCTION: Most reports on the outcome of Watch-and-Wait (W&W) in rectal cancer come from expert centres. This study reports on a broad implementation in the Netherlands. MATERIAL AND METHODS: The process of W&W implementation is described and the outcome of patients in a W&W registry between 2004 and 2022 analysed (regrowth, metastases, survival, and organ preservation). Three equally sized chronological cohorts were compared to capture any differences during implementation over time. RESULTS: W&W was gradually implemented in 18 high-volume hospitals coordinated by a single expert centre. One thousand and eighty patients with a clinical good response after (chemo)radiotherapy were included, with a median follow-up of 42 months (95% c.i. 40 to 44). At first response evaluation, 45% had a clinical complete response (cCR) and 55% near-complete reponse (nCR). In patients with nCR, 75% eventually achieved cCR, 14% underwent local excision, 2% received additional contact X-ray brachytherapy, and 10% underwent total mesorectal excision (TME) for persistent residual disease. Three-year actuarial local regrowth incidence was 23%. Three-year organ preservation rate was 76%. The 3-year distant metastases rate and overall survival were 10% and 97%. There were no significant differences in 3-year local regrowth or distant metastases between the three consecutive cohorts. In the two more recent cohorts more patients underwent TME for residual disease (13% versus 3%), likely due to a more liberal inclusion of patients with nCR. CONCLUSION: The results of W&W in rectal cancer patients in high-volume hospitals mirror those of expert centres.