Preoperative chemoradiotherapy using tegafur/uracil, oral leucovorin, and irinotecan (TEGAFIRI) followed by oxaliplatin-based chemotherapy as total neoadjuvant therapy for locally advanced rectal cancer: the study protocol for a phase II trial

BACKGROUND: Total neoadjuvant therapy (TNT) is a novel treatment strategy that is an alternative to preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer (LARC). However, an optimal protocol for TNT has not yet been established. The present study will be an open-label, single-arm, single-center trial to develop a new protocol. METHODS: Thirty LARC patients at high risk of distant metastasis will receive CRT consisting of long-course radiation, concurrent with tegafur/uracil, oral leucovorin, irinotecan (TEGAFIRI), followed by mFOLFOX-6 or CAPOX before undergoing surgery. DISCUSSION: Since previous findings showed a high percentage of grade 3–4 adverse events with the TEGAFIRI regimen for CRT and TNT, the primary outcome of this study will be safety and feasibility. Our regimen for CRT consists of the biweekly administration of irinotecan for good patient compliance. The novel combination approach of this treatment may improve the long-term outcomes of LARC. TRIAL REGISTRATION: Japan Registry of Clinical Trials jRCTs031210660. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-023-10941-z.