Radiotherapy Department, Ribeirão Preto Medical School Hospital and Clinics, University of São Paulo, São Paulo, Brazil.
Department of Physics, Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Int J Radiat Biol. 2021;97(2):120-125. doi: 10.1080/09553002.2021.1846818. Epub 2020 Nov 17.
Recently, low dose radiotherapy delivered to the whole lung has been proposed as treatment for the pneumonia due to COVID-19. Although there is biological plausibility for its use, the evidence supporting its effectiveness is scarce, and the risks associated with it may be significant. Thus, based on a virtual case simulation, we estimated the risks of radiation-induced cancer (RIC) and cardiac disease.
Lifetime attributable risks (LAR) of RIC were calculated for the lung, liver, esophagus, and breast of female patients. The cardiovascular risk of exposure-induced death (REID) due to ischemic heart disease was also calculated. The doses received by the organs involved in the treatment were obtained from a simulation of conformal radiotherapy (RT) treatment, delivering a dose of 0.5 Gy-1.5 Gy to the lungs. We considered a LAR and REID <1% as acceptable, 1-2% cautionary, and >2% unacceptable.
The lung was at the highest risk for RIC (absolute LAR below 5200 cases/100,000 and 2250 cases/100,000 for women and men, respectively). For women, the breast had the second-highest LAR, especially for young women. The liver and esophagus had LARs below 700/100,000 for both sexes, with a higher incidence of esophageal cancer in women and liver cancer in men. Regarding the LAR cutoff, we observed an unacceptable or cautionary LAR for lung cancer in all women and men <60 years with an RT dose >1 Gy. LAR for lung cancer with an RT dose of 1 Gy was cautionary for women >60 years of age and men <40 years of age. No LAR estimation was unacceptable for the RT dose ≤0.7 Gy in all groups irrespective of sex or age at exposure. Only 0.5 Gy had an acceptable REID.
A RT dose ≤0.5 Gy provides an acceptable LAR estimate (≤1%) for RIC and REID, irrespective of sex and age. The current ongoing trials should initially use doses ≤0.5 Gy to maintain the risks at an acceptable level and include only patients who fail or do not have any other treatment option.
最近，有人提议对新冠肺炎引起的肺炎采用低剂量全肺放射治疗。虽然其应用具有生物学合理性，但支持其有效性的证据很少，而且与之相关的风险可能很大。因此，基于虚拟病例模拟，我们估计了放射性癌症（RIC）和心脏病的风险。
计算了女性患者肺部、肝脏、食管和乳房的 RIC 终生归因风险（LAR）。还计算了因缺血性心脏病导致的暴露诱导死亡（REID）的心血管风险。通过对适形放疗（RT）治疗的模拟获得了参与治疗的器官所接受的剂量，该治疗向肺部输送 0.5Gy-1.5Gy 的剂量。我们认为 LAR 和 REID <1%为可接受，1-2%为警告，>2%为不可接受。
肺部发生 RIC 的风险最高（女性的绝对 LAR 分别为<5200 例/100,000 和 2250 例/100,000，男性）。对于女性，乳房的 LAR 次之，尤其是年轻女性。肝脏和食管的 LAR 均<700/100,000，女性患食管癌，男性患肝癌的发病率较高。对于 LAR 截止值，我们观察到对于 RT 剂量>1Gy 的所有<60 岁的女性和男性，肺癌的 LAR 为不可接受或警告。对于 RT 剂量为 1Gy 的女性>60 岁和男性<40 岁的肺癌，LAR 为警告。在所有人群中，无论性别或接触时的年龄如何，RT 剂量≤0.7Gy 时，均未发现不可接受的 LAR 估计值。只有 0.5Gy 时才有可接受的 REID。
RT 剂量≤0.5Gy 可提供 RIC 和 REID 的可接受 LAR 估计值（≤1%），无论性别和年龄如何。目前正在进行的试验最初应使用≤0.5Gy 的剂量，以将风险保持在可接受的水平，并仅包括那些失败或没有其他治疗选择的患者。
