ACCORD study: a national multi-centre study of the watch and wait approach in patients with rectal cancer in Aotearoa New Zealand.

Aim: The adoption of a watch and wait (W&W) approach in patients with rectal cancer, and a complete clinical response (cCR) following neoadjuvant therapy, is increasing worldwide. Despite this, pragmatic unbiased outcome data is limited. This study aimed to investigate national outcomes associated with W&W in Aotearoa New Zealand (AoNZ).

Methods: A national retrospective study of patients with adenocarcinoma of the rectum managed with a W&W approach between January 2015 and December 2022 in AoNZ was performed by STRATA, a student and trainee led collaborative network. The Cancer Registry and the New Zealand Ministry of Health National Minimum Data Set were linked to identify patients who had rectal cancer and who were treated with neoadjuvant therapy but not rectal resection. Research teams across 17 AoNZ hospitals then screened these patients for inclusion and data collection.

Results: One thousand five hundred and eighteen patients were screened across 17 hospitals, 133 met inclusion criteria. Median age was 71 years. Median follow-up was 2.2 years. The 2-year cumulative incidence of local regrowth was 18.2% (95% CI 10.7%-25.1%), of which 92% was present in the bowel wall, and 68% underwent surgery, all with curative intent. The 2-year cumulative distant metastasis rate was 8.8% (95% CI 3.0%-14.2%) and the 2-year overall survival was 94.8% (95% CI 90.4%-99.4%).

Conclusion: This nationwide study of a W&W approach has clinical outcomes similar to the international literature. This data will help guide further implementation of a W&W approach in the management of patients with rectal cancer and inform both clinicians and patients.