Inclusion Criteria:

- Eligible patients are 18 years or older and have histologically confirmed
adenocarcinoma of the rectum (defined as the distal border of the tumour less than 16
cm from the anal verge measured by rigid rectoscopy) with no evidence of distant
metastases (identified by abdominal ultrasound or CT scan and chest radiography).

- Patients in the adjuvant cohort have undergone R0-resection by total mesorectal
excision (TME) of a pT3-4 Nany or Tany Npositive non-metastatic rectal cancer.

- Patients treated in the neoadjuvant cohort need to have a clinical T3-4 Nany or Tany
Npositive tumour staged by endoscopic ultrasound, provided the lower border of the
tumour is located 0 - 16 cm from the anal verge measured by rigid rectoscopy and the
primary tumour is deemed resectable by TME surgery on the basis of clinical
assessment. Other eligibility criteria comprise: WHO status of zero or one; adequate
liver, renal, and bone marrow function defined as follows: leucocyte count >
3,500/µl, thrombocyte count > 100,000/µl, hemoglobin > 10.0 g/dl; serum bilirubine <
2.0 mg/dl, serum creatinine < 2.0 mg/dl.

Exclusion criteria:

- Prior treatment for rectal cancer, prior chemo- or immunotherapy, prior pelvic
radiotherapy, or a history of other malignant diseases within the past five years
with the exception of succesfully treated basal carcinoma of the skin or carcinoma in
situ of the uterine cervix.

- Participation in another trial, pregnancy, breast-feeding, unwillingness to use
effective contraception, or a medical condition or concomitant illness which could
potentially interfere with compliance to the protocol are regarded as exclusion
criteria, as well.