Neoadjuvant Therapy vs Standard Therapy in Locally Advanced Rectal Cancer

Radiotherapy 50 Gy 5 radiations per week of 2 Gy for 5 weeks

Fluorouracil 400 mg/m² D1-4 and folic acid 20mg/m2 D1-4 the first and fifth weeks of radiotherapy

oxaliplatin: 85 mg/m² in 2 hours at D1; folinic acid: 100 mg/m² simultaneously in 2 hours at D1 and D2 during the Oxaliplatin; bolus 5-fluorouracil (5-FU) 400mg/m² D1+D2; infusion 5-fluorouracil (5-FU): 600 mg/m² continuous infusion during 22hours at D1 and D2, every 14 days during 42 months (8 cycles).

Chemoradiotherapy 5 weeks (50 Grays (Gy), 2 Gy/session; 25 fractions) + fluorouracil/leucovorin 400 mg/m² 1-4 day the first and fifth weeks of radiotherapy. FOLOFX4 will be administrated for 8 cycles over a 16 week period. Patients will undergo re-staging within 6 weeks of their 8th cycle of FOLFOX. This will include MRI of the pelvis. If the reassessment reveals that there has been no disease progression compared to the pre-treatment evaluation and the patient remains a candidate for an R0 resection, the patient will proceed to definitive rectal cancer surgery within 8 weeks from the last chemotherapy dose. If the surgical oncologist's reassessment reveals that the patient is not a candidate for an R0 resection, the patient will proceed to standard pre-operative radiation with synchronous fluorouracil.