A phase I dose-escalation study to determine the maximum tolerated dose of radiotherapy, in combination with concomitant 5-FU chemptherapy, in patients with locally advanced rectal cancer with a positive circumferential resection margin (cCRM).

Local control is significantly worse in rectal cancer patients with a positive circumferential resection margin in the pathological specimen (p CRM). Preoperative radiotherapy with or without concomitant chemotherapy is the standard treatment modality in locally advanced rectal cancer at present. In the present phase-I study we want to evaluate the acute toxicity of dose-escalated radiotherapy of the tumor volume in this high risk group. Repeated imaging with Cone Beam CT (CBCT) will be used to determine adequate safety-margins around the boost volume. As secondary endpoints we want to evaluate the rate of negative pathological circumferential resection margins and the accuracy of tumor response prediction by [18-F]-fluor-2deoxy-D-glucose (FDG)-positron-emission tomography (PET) and diffusion-weighted (DW)-magnetic resonance imaging (MRI). Therfore FDG-PET and diffusion-MRI will be acquired at 3 time points: before, during and after radiotherapy.

Keywords:Diffusion-weighted MRI, Neo-adjuvant, Rectal cancer, Dose-escalation, Radiochemotherapy

Disciplines:Laboratory medicine, Palliative care and end-of-life care, Regenerative medicine, Other basic sciences, Other health sciences, Nursing, Other paramedical sciences, Other translational sciences, Other medical and health sciences