Introduction: The Watch-and-Wait (WW) strategy is a potential option for patients with rectal cancer who obtain a complete clinic response after neoadjuvant therapy. The aim of this study is to analyse the long-term oncological outcomes and perform a cost- effectiveness analysis in patients undergoing this strategy for rectal cancer.

Methods: The data of patients treated with the Watch-and-Wait strategy were prospectively collected from January 2015 to January 2020. A control group was created, matched 1:1 from a pool of 480 patients undergoing total mesorectal excision. An independent company carried out the financial analysis. Clinical and oncological outcomes were analysed in both groups. Outcome parameters included surgical and follow-up costs, quality-adjusted life years (QALYs) and the incremental cost per QALY gained or the incremental cost-effectiveness ratio (ICER).

Results: Forty patients were included in the Watch-and-Wait (WW) group, with 40 patients in the surgical group. During a median follow-up period of 36 months, metastasis-free survival (MFS) and overall survival (OS) were similar in the two groups. In the WW group, nine (22%) local regrowths were detected in the first two years. The permanent stoma rate was slightly higher after salvage surgery in the WW group compared to the surgical group (48.5 vs. 20%, p ≤ 0.01). The cost-effectiveness analysis was slightly better for the WW group, especially for low rectal cancer compared to medium-high rectal cancer (ICER = -108,642.1 vs. ICER = -42,423).

Conclusions: The WW strategy in locally advanced rectal cancer offers similar oncological outcomes with respect to the surgical group and excellent results in quality of life and cost outcomes, especially for low rectal cancer. Nonetheless, the complex surgical field during salvage surgery can lead to a high permanent stoma rate, therefore the careful selection of patients is mandatory.