Clinical Outcomes of Preoperative Hyperthermic Chemoradiotherapy for Locally Advanced Rectal Cancer

Background/Aim: We compared the clinical outcomes of preoperative hyperthermic chemoradiotherapy (HCRT) with outcomes after surgery alone in patients with locally advanced rectal cancer within 10 cm of the anal verge. Patients and Methods: We retrospectively evaluated 66 patients with clinical T3-T4 rectal cancer treated between 2012 and 2021 (surgery alone, n=30; HCRT, n=36). The HCRT regimen comprised intensity-modulated radiotherapy (50 Gy) with concurrent capecitabine and hyperthermia (once weekly for five sessions in total). Tumor volume reduction ratio (TVRR), postoperative outcomes, and survival were evaluated. Results: The sphincter-preserving treatment rate was significantly higher in the HCRT group than in the surgery-alone group (69.4% vs. 33.3%, p=0.003). The median TVRR after HCRT was 80.6%, and 87.5% of patients were classified as good responders. Among patients who underwent surgery, the crude overall postoperative complication rate was lower in the HCRT group than in the surgery-alone group (35.3% vs. 60.0%, p=0.048), whereas severe complications did not differ significantly between the groups. Three-year recurrence-free and overall survival did not differ significantly between the groups. Conclusion: Preoperative HCRT was associated with tumor regression and higher sphincter-preserving treatment rates without an apparent increase in severe postoperative morbidity. However, no survival benefit was found; the independent additive effect of hyperthermia beyond standard chemoradiotherapy remains unclear.