Predictive Value of 18F-FAZA in Rectum Cancer

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.