Inclusion Criteria:

- Histopatologically verified adenocarcinoma in the rectum

- T4 tumor eller T3 tumor < 10 cm from the anus and < 5 mm from the mesorectal fascie
measured by MR scan. At the distal part of the rectum the distance to the mesorectal
fascie is < 5 mm and therefore all T3 tumors are included in this area

- Suitable for preoperative radiation and chemotherapy

- No distant metastases

- Age >18 years

- Hematology ANC ≥1.5x10^9/l. Thrombocytes ≥ 100x10^9/l.

- Biochemistry Bilirubin ≤ 3 x UNL. ALAT ≤ 5 x UNL

- Creatinine ≤ UNL

- Contraception for fertile women

- Written and orally informed consent

Exclusion Criteria:

- Other malignant disease within 5 years, excl. non-melanotic skin cancer

- Previous radiation treatment of the pelvis

- Pregnant or breastfeeding women

- Surgery within 6 weeks prior to enrollment

- Serious concurrent medical disease

- Enrollment in study "A prospective observational study of patients with rectum cancer
after concomitant radiation and chemotherapy", where the patients are potientially
not operated.