Effect of hyperthermia on the hypoxic fraction in an experimental mammary carcinoma in vivo.
The influence of hyperthermia on the fraction of clonogenic hypoxic cells in a CaH mammary carcinoma was investigated using the TCD50 values for radiation treatment under normal or clamped conditions. A one-hour heat treatment at 41.5 and 42.5 degree C given four hours after radiation reduced the hypoxic fraction to 2.3 X 10(-1), 7.4 X 10(-3) and 6.5 X 10(-3) respectively, when compared with the content of hypoxic cells in non-heated tumours. The results indicate that moderate hyperthermia is able to destroy selectively a large proportion of the fraction of radioresistant hypoxic cells in a solid tumour. This effect is probably due to the increased heat sensitivity of cells in a chronically hypoxic and nutritionally deprived acidic environment.
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D006358:Hot Temperature / Q000627:therapeutic use*; D008325:Mammary Neoplasms, Experimental / Q000532:radiotherapy / Q000628:therapy*; D051379:Mice; D008809:Mice, Inbred C3H; D010100:Oxygen; D011836:Radiation Tolerance
D010100:Oxygen