Consolidation Versus Induction Chemotherapy in Total Neoadjuvant Therapy of Rectal Cancer With High Risk for Recurrence

The purpose of this study is to identify the most promising treatment sequence in total neoadjuvant therapy for locally advanced rectal cancer with a high risk of recurrence.

Inclusion Criteria:- histologically proven rectal adenocarcinoma * no distant metastases on CT scan (M0 disease) * at least one high risk factor for disease recurrence identified on magnetic resonance imaging (MRI): * T4 tumor (cT4) * N2 disease (cN2) * extramural venous invasion (cEMVI+) * positive lateral lymph nodes * distance of tumor to mesorectal fascia or positive lymph nodes is 1 mm or less (cMRF+) * capacity for informed consent * willingness to attend regular check-ups during and after treatment Exclusion Criteria:history of previous irradiation in the pelvic area * absolute contraindications for MR imaging * distant metastases cannot be reliably excluded * synchronous cancer * chronic inflammatory bowel disease