Urano M, Kenton L A, Kahn J
Edwin L. Steele Laboratory for Radiation Biology, Department of Radiation Medicine, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Int J Radiat Oncol Biol Phys. 1989 Feb;16(2):437-42. doi: 10.1016/0360-3016(89)90339-8.
The effect of hyperthermia on radiation carcinogenesis was investigated in the C3Hf/Sed mouse foot. The foot was irradiated under hypoxic conditions, in air, or under hyperbaric oxygen conditions to evaluate the oxygen effect. Hyperthermia at 43.5 degrees C for 45 min was given by immersing the animal foot into a constant temperature water bath. A malignant tumor in the irradiated foot was first observed congruent to 250 days after irradiation. Tumors developed in the irradiated area until day 850. RCD50, or 50% radiation carcinogenesis dose was the endpoint and was calculated based on the tumor incidence 650 days after irradiation. RCD50 following radiation given alone under hypoxic conditions was 66.3 (60.0-73.2) Gy, and the oxygen enhancement ratio (hypoxic/hyperbaric oxygen) was 3.0 (2.5-3.5). Radiation carcinogenesis was enhanced by hyperthermia given with a 20 min treatment interval with no significant alteration in the oxygen effect. Thermal enhancement was greatest when hyperthermia was given 20 min prior to irradiation (2.5 [2.2-2.9] under hypoxia). No thermal enhancement was observed when two treatments were given with a treatment interval of 2 days. The median time to develop a malignant tumor decreased with increasing radiation dose. This median time was shorter following combined hyperthermia and irradiation (423 days) than following radiation alone (504 days). Histological studies revealed that more than 80% of tumors were soft tissue sarcomas, and the most common tumor was fibrosarcoma. Squamous cell carcinoma was found in 7% of all tumors.
在C3Hf/Sed小鼠足部研究了热疗对辐射致癌作用的影响。将足部在缺氧条件下、空气中或高压氧条件下进行照射，以评估氧效应。通过将动物足部浸入恒温水浴中，在43.5℃下给予45分钟的热疗。照射后第250天首次在受照射的足部观察到恶性肿瘤。在照射区域的肿瘤持续发展至第850天。RCD50（即50%辐射致癌剂量）为研究终点，并根据照射后650天的肿瘤发生率进行计算。在缺氧条件下单独给予辐射后的RCD50为66.3（60.0 - 73.2）Gy，氧增强比（缺氧/高压氧）为3.0（2.5 - 3.5）。当热疗与辐射间隔20分钟给予时，辐射致癌作用增强，而氧效应无显著改变。当热疗在照射前20分钟给予时，热增强作用最大（缺氧条件下为2.5 [2.2 - 2.9]）。当两次治疗间隔2天给予时，未观察到热增强作用。发生恶性肿瘤的中位时间随辐射剂量增加而缩短。热疗与辐射联合后的中位时间（423天）比单独辐射后的中位时间（504天）短。组织学研究显示，超过80%的肿瘤为软组织肉瘤，最常见的肿瘤是纤维肉瘤。在所有肿瘤中，7%为鳞状细胞癌。
