Visualization of Rectal Cancer During Endoscopy, Using a Fluorescent Tracer

Inclusion Criteria:

* Biopsy-proven, newly diagnosed primary rectal adenocarcinoma, i.e. with the lowest part of the tumor less than 16 cm from the anal verge using a rigid rectoscope or flexible endoscope.
* Locally advanced tumor fulfilling at least one of the following criteria on pelvic MRI indicating high risk of failing locally and/or systemically:

  * Clinical stage (c)T4a
  * cT4b
  * Extramural vascular invasion (EMVI+)
  * N2 i.e. four or more lymph nodes in the mesorectum showing morphological signs on MRI indicating metastatic disease
  * positive mesorectal fascia (MRF), i.e. tumor or lymph node one mm or less from the mesorectal fascia
  * metastatic lateral nodes, \> 1 cm (lat Lymph Node+)
* Staging done within 5 weeks before randomization.
* No contraindications to chemotherapy, including adequate blood counts:

  * White blood count ≥4.0 x 109/L;
  * Platelet count ≥100 x 109/L;
  * Clinically acceptable haemoglobin levels;
  * Creatinine levels indicating renal clearance of ≥50 ml/min;
  * Bilirubin \<35 μmol/l
* Eastern Cooperative Oncology Group (ECOG) performance score \< 1.
* Patient is considered to be mentally and physically fit for chemotherapy as judged by the medical oncologist.
* Age ≥ 18 years.
* Written informed consent.
* Adequate potential for follow-up.

Exclusion Criteria:

* Extensive growth into cranial part of the sacrum (above S3) or the lumbosacral nerve roots indicating that surgery will never be possible even if substantial tumour down-sizing is seen.
* Presence of metastatic disease or recurrent rectal tumour. Familial Adenomatosis Polyposis coli (FAP), Hereditary Non-Polyposis Colorectal Cancer (HNPCC), active Crohn's disease or active ulcerative Colitis.
* Concomitant malignancies, except for adequately treated basocellular carcinoma of the skin or in situ carcinoma of the cervix uteri. Subjects with prior malignancies must be disease-free for at least 5 years.
* Known dihydropyrimidine dehydrogenase (DPD) deficiency.
* Any contraindications to MRI (e.g. patients with pacemakers).
* Medical or psychiatric conditions that compromise the patient's ability to give informed consent.
* Concurrent uncontrolled medical conditions.
* Any investigational treatment for rectal cancer within the past month.
* Pregnancy or breast feeding.
* Patients with known malabsorption syndromes or a lack of physical integrity of the upper gastrointestinal tract.
* Clinically significant (i.e. active) cardiac disease (e.g. congestive heart failure, symptomatic coronary artery disease and cardiac dysrhythmia, e.g. atrial fibrillation, even if controlled with medication) or myocardial infarction within the past 12 months.
* Patients with symptoms or history of peripheral neuropathy.