Proposal for a post-operative surveillance strategy for stage I colorectal cancer patients based on a novel recurrence risk stratification: a multicenter retrospective study.

Abstract

The recurrent risk of stage I colorectal cancer (CRC) is not clear, and the data regarding appropriate post-operative surveillance schedules in stage I CRC are scarce. We aimed to stratify stage I CRC based on the recurrence risk and evaluate optimal post-operative surveillance durations based on this stratification. We retrospectively analyzed the cases of 6607 stage I CRC patients from 24 institutions. To assess the patients' clinicopathological factors that impact recurrence-free survival (RFS), we performed univariate and multivariate analyses using Cox proportional hazards models. We divided the patients into classes based on their numbers of factors that were associated with poor RFI in the multivariate analysis. Recurrence occurred in 3.9% patients. The multivariate analysis revealed the independent factors for poor RFS: rectal cancer, T2 depth, presence of lymphatic invasion, high level of pre-operative carcinoembryonic antigen, and absence of D2-3 lymphadenectomy. We also divided the patients into three classes based on their numbers of these risk factors; the 3-year and 5-year RFS rates were 99.3% and 99.1% in the no-risk patients, 97.4% and 96.5% in the patients with 1-2 risks, and 92.1% and 90.0% in the patients with 3-5 risks, respectively. In the patients with no risk and in the patients with 1-2 risks after 3years post-surgery, ≤ 1% recurrence occurred. Thus, post-operative surveillance may be omitted in these populations. Our new classification properly stratified the recurrence risks of stage I CRC patients, and may help reduce unnecessary post-operative surveillance.