Response-guided Strategy Based on Induction Chemotherapy Without Routine Use of Radiotherapy for Locally Advanced Rectal Cancer.

Background/aim: Total neoadjuvant therapy (TNT) is promising in reducing distant metastasis and facilitating nonoperative management (NOM) in locally advanced rectal cancer. However, concerns arise regarding the quality of total mesorectal excision (TME) and local regrowth after NOM. This study investigated the feasibility of a response-guided strategy centered on induction chemotherapy to enhance patient selection and outcomes.

Patients and methods: From 2020 to 2023, patients with clinical Stage II/III lower rectal cancer, located within 10 cm from the anal verge, were enrolled. Induction chemotherapy used either an oxaliplatin-based doublet or triplet regimen over three months. Long-course chemoradiotherapy was administered selectively based on multidisciplinary evaluations, targeting either NOM or minimizing local recurrence for patients with mesorectal fascia (MRF) involvement.

Results: Eighteen consecutive patients were enrolled. At first restaging, 39% (seven patients) achieved a complete or near-complete response. Consequently, five patients underwent NOM after chemoradiotherapy, achieving a 100% TME-free survival rate. R0 resections were successful in all 13 surgical cases, including two patients with residual tumor who underwent TNT and one patient with MRF involvement even after TNT, as well as 10 patients without MRF involvement treated solely with induction chemotherapy, omitting chemoradiotherapy.

Conclusion: Induction chemotherapy effectively filters suitable candidates for NOM in locally advanced rectal cancer, suggesting a potential to omit routine radiotherapy. This approach highlights personalized treatment strategies and aims to enhance patients' quality of life by reducing unnecessary surgeries and preserving rectal function.