[Regression of Yoshida sarcoma during normoxia and hypoxia after fractionated irradiation].
OBJECTIVE
Tumor regression is one of the most important factors determinating the tumor control probability after radiotherapy. The changes in the regression of tumors during fractionated radiotherapy and the application of different radioprotectors or radiosensitizers make render to assess their effectivity.


METHODS
The effect of hypoxic breathing (8.1% O2) on the tumor regression of Yoshida sarcoma was studied using rats of Wistar strain. Different fractionation schedules were used: 10 x 3 Gy, 6 x 5 Gy and 3 x 10 Gy.


RESULTS
No significant changes in the tumor regression after radiotherapy in any group in any time independent from respiratoric hypoxia were recorded. The tumor regression rate was significantly influenced by treatment schedule (p < 0.0005).


CONCLUSIONS
Our results support the hypothesis of hypoxy-radiotherapy: The acute hypoxic hypoxia, caused due the breathing of hypoxic gas mixture with 8 to 10% oxygen, did not influence the radiation induced tumor regression in animal experiment. For this criterium no protection can be shown. The influence of hypoxy-radiotherapy on the local tumor control is necessary to evaluate in further experiments.
Strnad
V
V
Klinik und Poliklinik für Strahlentherapie, Universität Erlangen-Nürnberg.
Kamprad
F
F
Jahns
J
J
Meyer
M
M
Böhme
R
R
Madaj-Sterba
P
P
Kirschner
M
M
Sauer
R
R
D000208:Acute Disease; D000818:Animals; D000860:Hypoxia / Q000503:physiopathology; D008962:Models, Theoretical; D009458:Neuroleptanalgesia; D010100:Oxygen / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D051381:Rats; D017208:Rats, Wistar; D012119:Respiration; D012517:Sarcoma, Yoshida / Q000473:pathology / Q000532:radiotherapy*; D013997:Time Factors
D010100:Oxygen