Patients with unresectable primary rectal cancer or with unresectable local recurrence without distant metastases are randomly allocated to control or experimental arm. The preoperative treatment in the control arm is conventionally fractionated chemoradiation with 50.4 Gy total dose in 28 fractions of 1.8 Gy over 5.5 weeks simultaneously with 5-Fu, leucovorin and oxaliplatin. Experimental group receive 25 Gy in 5 fractions of 5 Gy over 5 days and after one week interval - consolidating chemotherapy of 3 courses of FOLFOX4. Surgery should be curried out 10-11 weeks from beginning of radiation and at least 4 weeks from the last dose of fluorouracil or radiation. The study hypothesis is that the short-course preoperative radiotherapy with consolidating chemotherapy produce at least 10% increase of the rate of R0 resection compared to preoperative chemoradiation.