Neoadjuvant chemotherapy with or without oxaliplatin after short-course radiotherapy in high-risk rectal cancer: A subgroup analysis from a prospective study.

Aim: To evaluate the role of oxaliplatin in neoadjuvant chemotherapy delivered after short-course irradiation.

Background: Using oxaliplatin in the above setting is uncertain.

Patients And Methods: A subgroup of 136 patients managed by short-course radiotherapy and 3 cycles of consolidation chemotherapy within the framework of a randomised study was included in this post-hoc analysis. Sixty-seven patients received FOLFOX4 (oxaliplatin group) while oxaliplatin was omitted in the second period of accrual in 69 patients because of protocol amendment (fluorouracil-only group).

Results: Grade 3+ acute toxicity from neoadjuvant treatment was observed in 30% of patients in the oxaliplatin group vs. 16% in the fluorouracil-only group ( = 0.053). The corresponding proportions of patients having radical surgery or achieving complete pathological response were 72% vs. 77% (odds ratio [OR] = 0.88; 95% confidence interval [CI]: 0.39-1.98;  = 0.75) and 15% vs. 7% (OR = 2.25; 95% CI: 0.83-6.94;  = 0.16), respectively. The long-term outcomes were similar in the two groups. Overall and disease-free survival rates at 5 years were 63% vs. 56% ( = 0.78) and 49% vs. 44% ( = 0.59), respectively. The corresponding numbers for cumulative incidence of local failure or distant metastases were 33% vs. 38% (hazard ratio [HR] = 0.89; 95% CI: 0.52-1.52;  = 0.68) and 33% vs. 33% (HR = 0.78; 95% CI: 0.43-1.40; = 0.41), respectively.

Conclusion: Our findings do not support adding oxaliplatin to three cycles of chemotherapy delivered after short-course irradiation.