Intentional Watch and Wait or Organ Preservation Surgery Following Neoadjuvant Chemoradiotherapy Plus Consolidation CAPEOX for MRI-defined Low-risk Rectal Cancer: Findings From a Prospective Phase 2 Trial (PKUCH-R01 Trial, NCT02860234).

"The authors report no conflicts of interest."

"Supported by The Beijing Municipal Science & Technology Commission Capital Clinical Research Special Fund (Z151100004015105); National Natural Science Foundation of China (81773214); Beijing Hospitals Authority Clinical Medicine Development of Special Funding Support, code: (ZYLX202116)."

"The baseline data analysis showed that 48% of locally advanced rectal cancers could be downstaged to stage ypT0-2N0 following 22f-IMRT with concurrent capecitabine. We assumed that at least 24% of locally advanced rectal cancers could be candidates for post-IMRT LE or W&W and that the OPR would increase to 40% in low-risk rectal cancers that were treated by LE or W&W following IMRT plus consolidation CAPEOX. Based on a superiority design, this study needed to recruit 64 patients to test this hypothesis, with 85% power (exact binomial test for proportions, α=5%, 1-sided). We anticipated ∼10% loss to follow-up and, therefore, planned to recruit additional 8 patients or close recruitment after 64 eligible patients had been enrolled. Most of the data are descriptive because of the single-arm nature of this prospective study. We estimated the cumulative incidences of local regrowth, NR-DFS, TME-free survival, and stoma-free survival with the Kaplan-Meier (KM) method to depict the time-to-event parameters. All statistical analyses were performed in SPSS for Macintosh, IBM SPSS statistics for Macintosh, Version 20.0 (IBM Corp., Armonk, NY). This study is registered at ClinicalTrials.gov with the identifier NCT02860234."