Scott Bobby R, Walker Dale M, Walker Vernon E
Lovelace Respiratory Research Institute, Albuquerque, New Mexico.
Nonlinearity Biol Toxicol Med. 2004 Jul;2(3):185-211. doi: 10.1080/15401420490507602.
A protective apoptosis-mediated (PAM) process that is turned on in mammalian cells by low-dose photon (X and gamma) radiation and appears to also be turned on by the genotoxic chemical ethylene oxide is discussed. Because of the PAM process, exposure to low-dose photon radiation (and possibly also some genotoxic chemicals) can lead to a reduction in the risk of stochastic effects such as problematic mutations, neoplastic transformation (an early step in cancer occurrence), and cancer. These findings indicate a need to revise the current low-dose risk assessment paradigm for which risk of cancer is presumed to increase linearly with dose (without a threshold) after exposure to any amount of a genotoxic agent such as ionizing radiation. These findings support a view seldom mentioned in the past, that cancer risk can actually decrease, rather than increase, after exposure to low doses of photon radiation and possibly some other genotoxic agents. The PAM process (a form of natural protection) may contribute substantially to cancer prevention in humans and other mammals. However, new research is needed to improve our understanding of the process. The new research could unlock novel strategies for optimizing cancer prevention and novel protocols for low-dose therapy for cancer. With low-dose cancer therapy, normal tissue could be spared from severe damage while possibly eliminating the cancer.
本文讨论了一种保护性凋亡介导（PAM）过程，该过程在哺乳动物细胞中由低剂量光子（X射线和γ射线）辐射开启，并且似乎也可由基因毒性化学物质环氧乙烷开启。由于PAM过程，暴露于低剂量光子辐射（以及可能的一些基因毒性化学物质）可导致诸如问题突变、肿瘤转化（癌症发生的早期步骤）和癌症等随机效应风险的降低。这些发现表明有必要修订当前的低剂量风险评估范式，在该范式中，暴露于任何量的基因毒性剂（如电离辐射）后，癌症风险被假定随剂量呈线性增加（无阈值）。这些发现支持了一种过去很少被提及的观点，即暴露于低剂量光子辐射以及可能的其他一些基因毒性剂后，癌症风险实际上可能降低而非增加。PAM过程（一种自然保护形式）可能对人类和其他哺乳动物的癌症预防有重大贡献。然而，需要新的研究来增进我们对该过程的理解。新的研究可能会开启优化癌症预防的新策略以及癌症低剂量治疗的新方案。通过低剂量癌症治疗，正常组织可免受严重损伤，同时有可能消除癌症。
