Short-Course Radiotherapy Followed by Consolidation Chemotherapy Is Safe and Effective in Locally Advanced Rectal Cancer: Comparative Short-term Results of Multicenter Propensity Score Case-Matched Study

Abstract

BACKGROUND: Consolidation chemotherapy strategies have demonstrated improved pathological complete response and tumor downstaging rates for patients diagnosed with rectal cancer. OBJECTIVE: This study aimed to compare perioperative outcomes and pathological complete response rates among different neoadjuvant treatment strategies in patients undergoing total mesorectal excision for locally advanced rectal cancer. DESIGN: Propensity score case-matched study. SETTING: High-volume tertiary care centers. PATIENTS: Consecutive patients undergoing curative total mesorectal excision between January 2014 and June 2021 were queried. INTERVENTIONS: Patients were divided into 3 groups: long-course chemoradiation therapy with (N = 128) or without (N = 164) consolidation chemotherapy or short-course radiotherapy (N = 53) followed by consolidation chemotherapy. MAIN OUTCOME MEASURES: Demographics, preoperative tumor characteristics, histopathologic outcomes, and postoperative complication rates were reviewed and compared. Propensity score match analysis was conducted. RESULTS: A total of 345 patients (mean age: 58 +/- 12 years; female: 36%) met the study inclusion criteria. Time interval from neoadjuvant treatment until surgery was longer for patients receiving consolidation chemotherapy (p < 0.001). Pathological complete response rates were comparable among patients receiving long-course chemoradiation therapy (20.3%) and short-course radiotherapy with consolidation chemotherapy (20.8%) compared to long-course chemoradiation therapy alone (14.6%) (p = 0.36). After the propensity score case-matched analysis, 48 patients in the long-course chemoradiation therapy with consolidation chemotherapy group were matched to 48 patients in the short-course radiotherapy with consolidation chemotherapy group. Groups were comparable with respect to age, sex, clinical stage, tumor location, type of surgical approach, and technique. Pathological complete response rate was comparable between the groups (20.8% and 18.8%, p = 0.99). LIMITATIONS: Study was limited by its retrospective nature. CONCLUSIONS: Among recent neoadjuvant treatment modalities, pathological complete response rates, and short-term clinical outcomes were comparable. Short-course radiotherapy with consolidation chemotherapy is safe and effective as long-course chemoradiation therapy as in a short-term period.