Short-Course Radiation Integrated With Immunochemotherapy Gives a Higher Pathological Complete Response Compared With the Long-Course Chemoradiation With Chemotherapy in the Total Neoadjuvant Therapy for Local Advanced Rectal Carcinoma in the Real World: a Retrospective Study

BACKGROUND: Total neoadjuvant therapy is the recommended modality for patients with locally advanced rectal carcinoma and those whose lesions are less than 5 centimeters from the anal verge. The optimal integration of total neoadjuvant therapy remains unclear. OBJECTIVE: This study aims to evaluate the efficacy of short-course radiation integrated with immunochemotherapy and long-course chemoradiation plus chemotherapy as modalities of total neoadjuvant therapy. DESIGN: Patients diagnosed with rectal carcinoma who received radiation integrated in total neoadjuvant therapy from January 2021 to January 2025 at the First Affiliated Hospital of Zhengzhou University were reviewed. Kaplan-Meier survival analysis was used for survival analysis. SETTINGS: This study was a retrospective study conducted at the First Affiliated Hospital of Zhengzhou University. PATIENTS: There were 128 patients enrolled in the short-course radiation integrated with immunochemotherapy group, and 64 patients enrolled in the long-course chemoradiation plus chemotherapy group. MAIN OUTCOME MEASURES: The primary end-point was pathological complete response. The secondary endpoints were the rate of sphincter-preservation, disease-free survival, and overall survival. RESULTS: The short-course radiation integrated with the immunochemotherapy group had a significantly higher pathological complete response rate than the long-course chemoradiation group (42.2% vs. 15.6%, p = 0.001). With a median follow-up of 42.3 months (95% CI: 40.538-43.990), the median disease-free survival was not reached versus 28.3 months ( p = 0.02, hazard ratio = 0.46, 95% CI: 0.205-1.040), respectively. The median overall survival was not reached ( p = 0.02, hazard ratio = 0.33, 95% CI: 0.118-0.910). The rate of sphincter-preservation was 75.8% versus 65.6% ( p = 0.138), respectively. LIMITATIONS: Biases resulting from the retrospective nature of this study. The sample size of the two groups was 128 and 64, resulting in a 2:1 allocation ratio, which may decrease the statistical power. CONCLUSION: The integration of short-course radiation plus immunochemotherapy gives a higher pathological complete response compared with the traditional long-course chemoradiation in the modality of total neoadjuvant therapy. The former integration presents a trend of dominance in long-term survival. See Video Abstract.