Increased Pathologic Downstaging with Induction versus Consolidation Chemotherapy in Patients with Locally Advanced Rectal Cancer Treated with Total Neoadjuvant Therapy-A National Cancer Database Analysis

Total neoadjuvant therapy (TNT) is the recommended treatment for locally advanced rectal cancer. The optimal sequence of TNT is debated: induction (chemotherapy first) or consolidation (chemoradiation first)? We aim to evaluate the practice patterns and clinical outcomes of total neoadjuvant therapy with either induction or consolidation regiments in the United States for patients with locally advanced rectal cancer. Methods: This is a retrospective analysis of the National Cancer Database for patients with clinical stage II or stage III rectal cancer, diagnosed between 2006 and 2017, who underwent total neoadjuvant therapy followed by surgery. Results: From 2006 to 2017, we identified 8999 patients and found that the utilization of induction chemotherapy increased from 2.0% to 35.0%. TNT resulted in pathologic downstaging 46.7% of the time and a pathologic complete response 11.6% of the time. Induction chemotherapy lead to higher pathologic downstaging (58% vs. 44.7%, p < 0.001) and pathologic complete responses (16.8% vs. 10.7%, p < 0.001). Similar trends held true in a multivariate analysis and subset analysis of stage II and III disease. Conclusions: These findings suggest that induction chemotherapy may be preferred over consolidation chemotherapy when downstaging prior to oncologic resection is desired. The optimal treatment plan for total neoadjuvant therapy is multi-factorial and requires further elucidation.