P-225 The addition of oxaliplatin increases pathological complete response: a meta-analysis of randomized controlled trials on radiochemotherapy in rectal cancer

Abstract

Introduction: The standard treatment of locally advanced rectal cancer consists of neoadjuvant radio‐ or radiochemotherapy followed by total mesorectal excision. The optimal treatment strategy for patients who do not accept stoma or are not suitable for rectal surgery has not been yet established. Usually, the standard radiochemotherapy with 5‐fluorouracil or capecitabine plus watch‐and‐wait strategy is suggested. There are ongoing prospective studies to confirm long‐term outcomes of this approach worldwide. The question is if the addition of oxaliplatin can result in higher incidence of pathological complete response (pCR) in rectal cancer patients. Methods: Five randomized controlled studies reporting pCR and toxicity data were identified by database searches. The study outcomes were extracted from publications. Calculations were performed using Review Manager 5.3. Results: The meta‐analysis using fixed effect model performed on the cohort of 4821 patients clearly indicates the significant increase of pCR rate in resection specimens of patients treated with oxaliplatin add‐on when compared with fluoropyrimidine‐based radiochemotherapy (HR 1.20; 95% CI 1.03‐1.40; p < 0.02). Such a treatment was related with an increase of grade 3 and 4 toxicities according to Common Terminology Criteria for Adverse Events (HR 1.63; 95% CI 1.43‐1.94; p < 0.00001), especially diarrhea (HR 2.05; 95% CI 1.65‐2.53; p < 0.00001). However, it did not translate into the significant increase of toxic deaths (13 of 1931 in oxaliplatin group vs 7 of 1944 in controls, p = 0.35). Conclusion: Despite the limited value in a neoadjuvant treatment, the addition of oxaliplatin to fluoropyrimidine increases the chance of pCR after radiochemotherapy. Such a treatment may be an option for patients willing to follow watch‐and‐wait strategy if pCR is achieved. Due to excessive toxicity, this approach should not be considered as an option for patients not suitable for rectal surgery due to co‐morbidities, biological age or general performance status.