Does the addition of oxaliplatin to preoperative chemoradiation benefit cT4 or fixed cT3 rectal cancer treatment? A subgroup analysis from a prospective study.

BACKGROUND: Whether there is any benefit derived from adding oxaliplatin to fluoropyrimidine-based preoperative chemoradiation is currently unknown in cases of advanced cT3 or cT4 tumours. Our aim was to evaluate this issue by analysing a randomized trial, which compared two schedules of preoperative treatment (chemoradiation vs. 5 × 5 Gy with 3 cycles of consolidation chemotherapy) for cT4 or fixed cT3 rectal cancer. PATIENTS AND METHODS: Delivery of oxaliplatin was mandatory to the first part of the study. For the second part, its delivery in both treatment-assigned groups was left to the discretion of the local investigator. We analysed a subgroup of 272 patients (136 in the oxaliplatin group and 136 in the fluorouracil-only group) from institutions that had omitted oxaliplatin in the second part of the study. RESULTS: Circumferential resection margin negative (CRM-) status rate was 68% in the oxaliplatin group and 70% in the fluorouracil-only group, p = 0.72. The pathological complete response rate (pCR) was correspondingly 14% vs. 7%, p = 0.10. Following multivariable analysis, when comparing the CRM- status in the oxaliplatin group to the fluorouracil-only group, the odds ratio was 0.79 (95 CI 0.35-1.74), p = 0.54; there being no interaction between concomitant chemoradiation and 5 × 5 Gy with consolidation chemotherapy; pinteraction = 0.073. For pCR, the corresponding results were 0.47 (95 CI 0.19-1.16), p = 0.10, pinteraction = 0.84. CONCLUSION: No benefit was found of adding oxaliplatin in terms of CRM nor pCR rates for either concomitant or sequential settings in preoperative radiochemotherapy for very advanced rectal cancer.

Long-course oxaliplatin-based preoperative chemoradiation versus 5 × 5 Gy and consolidation chemotherapy for cT4 or fixed cT3 rectal cancer: results of a randomized phase III study.

BACKGROUND: Improvements in local control are required when using preoperative chemoradiation for cT4 or advanced cT3 rectal cancer. There is therefore a need to explore more effective schedules. PATIENTS AND METHODS: Patients with fixed cT3 or cT4 cancer were randomized either to 5 × 5 Gy and three cycles of FOLFOX4 (group A) or to 50.4 Gy in 28 fractions combined with two 5-day cycles of bolus 5-Fu 325 mg/m(2)/day and leucovorin 20 mg/m(2)/day during the first and fifth week of irradiation along with five infusions of oxaliplatin 50 mg/m(2) once weekly (group B). The protocol was amended in 2012 to allow oxaliplatin to be then foregone in both groups. RESULTS: Of 541 entered patients, 515 were eligible for analysis; 261 in group A and 254 in group B. Preoperative treatment acute toxicity was lower in group A than group B, P = 0.006; any toxicity being, respectively, 75% versus 83%, grade III-IV 23% versus 21% and toxic deaths 1% versus 3%. R0 resection rates (primary end point) and pathological complete response rates in groups A and B were, respectively, 77% versus 71%, P = 0.07, and 16% versus 12%, P = 0.17. The median follow-up was 35 months. At 3 years, the rates of overall survival and disease-free survival in groups A and B were, respectively, 73% versus 65%, P = 0.046, and 53% versus 52%, P = 0.85, together with the cumulative incidence of local failure and distant metastases being, respectively, 22% versus 21%, P = 0.82, and 30% versus 27%, P = 0.26. Postoperative and late complications rates in group A and group B were, respectively, 29% versus 25%, P = 0.18, and 20% versus 22%, P = 0.54. CONCLUSIONS: No differences were observed in local efficacy between 5 × 5 Gy with consolidation chemotherapy and long-course chemoradiation. Nevertheless, an improved overall survival and lower acute toxicity favours the 5 × 5 Gy schedule with consolidation chemotherapy. CLINICAL TRIAL NUMBER: The trial is registered as ClinicalTrials.gov number NCT00833131.