[Preoperative radiotherapy in hypoxia in the complex treatment of the rectal carcinoma--complications]

Preoperative radiotherapy is considered to be the standard approach in the treatment of the rectal carcinoma. Acute hypoxia decreases partial pressure of oxygen in healthy tissues immediately, but in the tumor after 30 min of duration. There is a higher radioresistance of healthy tissues in this interval because of lower oxygenation compared with normooxic status and the tumor is still relatively good oxygenated. This fact theoretically enables higher doses of radiotherapy and lower adverse effects. The aim of this study was to evaluate short and long term complications after preoperative radiotherapy of rectal carcinoma in hypoxia.

Between April 1991 and October 2000, 127 patients with the rectal carcinoma were treated preoperatively with locoregional accelerated hypofractionated radiotherapy in hypoxic conditions in Masaryk Memorial Cancer Institute. The dosis was up to 8 x 4 Gy. Acute hypoxia was induced during irradiation by ventilation of a hypoxic gas mixture containing 7.8-8.0% oxygen for totally 7-8 min. Operation was performed till 24 hours.

There was no complication concerning with breathing of hypoxic gas mixture. A 30 day postoperative mortality was 0.8%. A 30 day postoperative morbidity was 31.7%. An anastomotic leakage occurred in 6.5%. Chronic gastrointestinal disorders occurred in 16.1% patients.

Preoperative irradiation in hypoxic conditions is safe and efficient procedure. It permits safe administration of doses higher than those tolerated by normooxic conditions. Type and frequency of complications are comparable with other preoperative regimens.