Induction chemotherapy for locally advanced rectal cancer.

Prior treatment

• Evidence of metastatic disease at time of inclusion or within six months prior to inclusion except for patients with enlarged iliac or inguinal lymph nodes and aspecific lung nodules
• Any chemotherapy within the past 6 months
• Previous radiotherapy in the pelvic area precluding chemoradiotherapy with a dose of 50-50.4 Gy
• Any contraindication to undergo surgery, as determined by the surgeon and/or anaesthesiologist
• Concurrent malignancies that interfere with the planned study treatment or the prognosis of the resected tumour

Other illness

• Any contraindication for the planned systemic therapy (e.g. severe allergy, pregnancy, kidney dysfunction and thrombocytopenia), as determined by the medical oncologist
• Any contraindication for the planned chemoradiotherapy (e.g. severe allergy to the chemotherapy agent or no possibility to receive radiotherapy), as determined by the medical oncologist and/or radiation oncologist

Other

• Homozygous DPD deficiency

• 18 years or older
• WHO performance score 0-1
• Fit for (modified dose) triple chemotherapy (FOLFOXIRI)
• Histopathologically confirmed rectal cancer
• Lower border of the tumour located on or below the sigmoidal take-off as established on MRI of the pelvis
• Confirmed high-risk locally advanced rectal cancer, at high risk of treatment failure, meeting one of the following imaging based criteria: *Tumour invasion of the mesorectal fascia (MRF+); *The presence of grade 4 extramural venous invasion (mrEMVI); *The presence of tumour deposits (TD); *The presence of bilateral extramesorectal lymph nodes with a short-axis size ≥ 7mm (LLN) or extensive LLN involving pelvic side wall structures, at high risk of an incomplete resection
• Resectable disease as determined on magnetic resonance imaging (MRI) or deemed resectable disease after neo-adjuvant treatment (Expected gross incomplete resection with overt tumour remaining in the patient after resection, tumour invasion in the neuroforamina, encasement of the sciatic nerve and invasion of the cortex from S2 and upwards are considered not resectable)
• Written informed consent