出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/08/20 13:54:29」(JST)
A radiosensitizer is a drug that makes tumor cells more sensitive to radiation therapy.
Conventional chemotherapeutics are currently being used in conjunction with radiation therapy to increase its effectiveness. Examples include the fluoropyrimidines, gemcitabine and platinum analogs; fluoropyrimidines increase sensitivity by dysregulating S-phase cell cycle checkpoints in tumor cells. Gemcitabine progresses through a similar mechanism, causing cells in the S-phase to disrepair DNA damage caused by the radiation. Platinum analogs such as cisplatin inhibit DNA repair by cross linking strands, and so exacerbate the effects of DNA damage induced by radiation.[1]
One of the major limitations of radiotherapy is that the cells of solid tumors become deficient in oxygen. Solid tumors can outgrow their blood supply, causing a low-oxygen state known as hypoxia. Oxygen is a potent radiosensitizer, increasing the effectiveness of a given dose of radiation by forming DNA-damaging free radicals. Tumor cells in a hypoxic environment may be as much as 2 to 3 times more resistant to radiation damage than those in a normal oxygen environment.[2] Much research has been devoted to overcoming this problem including the use of high pressure oxygen tanks, blood substitutes that carry increased oxygen, hypoxic cell radiosensitizers such as misonidazole and metronidazole, and hypoxic cytotoxins, such as tirapazamine. A newer approach involves the use of an oxygen diffusion-enhancing compound to re-oxygenate hypoxic tumor tissue.[3] One such compound, trans sodium crocetinate, is currently being tested in a multi-center clinical trial in 59 patients newly diagnosed with glioblastoma multiforme.[4]
This article incorporates public domain material from the U.S. National Cancer Institute document "Dictionary of Cancer Terms".
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| リンク元 | 「放射線増感剤」「radiation sensitizer」 |