Schaffer Moshe, Schaffer Pamela M, Jori Giulio, Corti Luigi, Sotti Guido, Hofstetter Alfons, Dühmke Eckhart
Department of Radiation Therapy, University of Munich, Germany.
Tumori. 2002 Sep-Oct;88(5):407-10. doi: 10.1177/030089160208800511.
Ionizing irradiation is a well-established therapeutic modality for cancer. Photodynamic therapy (PDT), especially with 5-ALA and Photofrin, is highly effective in some tumor types. Chemical modifiers, so-called radiosensitizers, are used in order to increase the efficacy of radiotherapy. Most of the known and routinely used radiosensitizers are not tumor selective, so that the normal tissue reaction toxicity is also increased. In the present study we investigated whether a porphyrin derivative that is currently used as a tumor-photosensitizing agent in photodynamic therapy (PDT) may also act as a tumor-specific radiosensitizer.
For our investigation we used Balb/c mice implanted with Lewis sarcoma and irradiated with 3 Gy combined with injection of 5-ALA or Photofrin at various concentrations before irradiation.
5-ALA had no effect as a radiosensitizer at any of the concentrations examined. Photofrin at a concentration of 5 mg/kg proved to be a chemical modifier of ionizing radiation, delaying tumor growth and reducing the overall tumor volume by about 50% after six days.
Photofrin has marked efficacy as a radiosensitizer and can be used in the future as a selective tumor radiosensitizer.
电离辐射是一种成熟的癌症治疗方式。光动力疗法（PDT），尤其是使用5-氨基乙酰丙酸（5-ALA）和光敏素，在某些肿瘤类型中非常有效。化学修饰剂，即所谓的放射增敏剂，被用于提高放射治疗的疗效。大多数已知且常规使用的放射增敏剂不具有肿瘤选择性，因此正常组织反应毒性也会增加。在本研究中，我们调查了一种目前在光动力疗法（PDT）中用作肿瘤光敏剂的卟啉衍生物是否也可作为肿瘤特异性放射增敏剂。
在我们的研究中，使用植入了Lewis肉瘤的Balb/c小鼠，在照射前以3戈瑞的剂量进行照射，并注射不同浓度的5-ALA或光敏素。
在所检测的任何浓度下，5-ALA均无放射增敏作用。浓度为5毫克/千克的光敏素被证明是电离辐射的化学修饰剂，可延迟肿瘤生长，并在六天后使肿瘤总体积减少约50%。
光敏素作为放射增敏剂具有显著疗效，未来可作为选择性肿瘤放射增敏剂使用。
