Radiation, a two-edged sword: From untoward effects to fractionated radiotherapy

Abstract

Radiations in medicine cover a wide range of applications, predominantly in diagnostic imaging and radiotherapy, encompassing photons (x-and γ-rays) and particle radiation, as well as with the use of liquid sources in nuclear medicine focusing on physiological functional imaging, tumour detection or targeted radiotherapy. The biological interactions of ionizing radiation leads naturally to questions of benefits and risk following dose exposures. The inherent properties of ionizing radiation in sterilising dividing cells can offer immense benefits with respect to tumour control, but radiation can also deliver potential harm in the form of normal tissue toxicity or carcinogenesis. The advances in radiation technology, offering accurate and reliable dose delivery, in concert with greater understanding of the underpinning radiobiological effects are creating an ever-growing ability to extract maximum benefit and minimise risk. The radiobiological effects fall broadly under the headings of mutagenesis, chromosomal aberrations, radiation induced genomic instability and cell death. The enormity of evidence derived from these underlie the mechanism of the six Rs of controlled radiotherapy: repair, repopulation, reoxygenation, redistribution, radiosensitivity and most recently, remote bystander cellular effects (including low dose hyper-radiosensitivity, adaptive response, hormesis, abscopal effect and immune response). Herein, we seek to discuss how such understanding leads to optimised radiotherapy.

The need for paradigm shift: prognostic significance and implications of standard therapy-related systemic immunosuppression in glioblastoma for immunotherapy and oncolytic virotherapy

“…Temozolomide is not a potent inducer of bona fide immunogenic cell death in human glioblastoma cells ( 150 – 152 ) and is not included in the shortlist of anti-cancer chemotherapeutics with the capacity to consistently induce immunogenic cell death ( 153 ). Although ionizing radiation can induce immunogenic cell death, it is critical to realize that conventional radiation treatment trigger a combination of cell death processes, such as apoptosis, necrosis, autophagy, mitotic catastrophe, and senescence, eliciting both immune-activating and suppressing responses ( 154 ). Additionally, it is widely recognized that immunogenic cell death cannot drive anti-cancer immunity in the presence of general immunological defects.…”

Low radiation dose to treat pneumonia and other inflammations

“…This is suggested to stimulate many of the natural protection systems of the body that normally cope with endogenous oxidative stress and the effects of toxins, injuries, diseases, etc (5,30). If lowdose γ-radiation occurs in the hormetic dose and dose-rate range, these are suggested to function much more intensely (4,12,22,(26)(27)(28)(30)(31)(32)(33)(34). Here, the complexity associated with the production of dedicated short-lived radionuclides for targeted α-emitting therapies can be compared against the relative ease of fabricating radon gas sources from the ubiquitous supply of naturally occurring 226 Ra.…”

Effects of Bismuth Oxide Nanoparticles, Cisplatin and Baicalein-rich Fraction on ROS Generation in Proton Beam irradiated Human Colon Carcinoma Cells

“…1 Charged particles therapies have been found to cause more damages due to double-strand breakage as well as reducing the cellular repairability and the cell-cycle dependency. 2 Proton beam radiotherapy has a broad-slow-rising entrance area before the sharp-rising Bragg peak, which is useful to treat deep-seated tumors without harming the normal healthy tissues. 3 The potential of proton beam therapy have led to more research and clinical endeavor in cancer treatment using ion beams.…”