Strategies to optimize radiotherapy based on biological responses of tumor and normal tissue

Abstract

Abstract. Rapid developments in radiation oncology are currently taking place. Radiation-induced responses are being increasingly used for radiotherapy modification based on advancements in radiobiology. In the process of radiation treatment, radiobiological responses of tumor and normal tissue in patients are monitored non-invasively by a variety of techniques including imaging, biological methods and biochemical assays. Information collected using these methods and data on responses are further incorporated into radiotherapy optimization approaches, which not only include the optimization of radiation treatment planning, such as dose distributions in targets and treatment delivery, but also include radiation sensitivity modification and gene radiotherapy of the tumor and normal tissue. Hence, the highest tumor control rate is obtained with the utmost protection being afforded to normal tissue under this treatment modality.

Activation of NRF2 by topical apocarotenoid treatment mitigates radiation-induced dermatitis

“…Interestingly, studies have shown that systemic upregulation of NRF2 can be radioprotective [ 60 ], while our own previous work has indicated that bixin can upregulate NRF2 systemically causing skin photoprotection [ 28 , 61 ]. However, in the context of this study, topical bixin administration seems preferable as it could limit NRF2 induction to the skin, thus minimizing NRF2 modulation throughout the body, and ultimately maintaining the desired sensitivity of specific tissues to radiotherapy [ [62] , [63] , [64] ]. While IR effects on cultured and epidermal keratinocytes are the primary focus of these experiments, the role of inflammatory factors including immune cell infiltration and response, all of which might be subject to modulation by NRF2, deserves further studies as it was not addressed in this prototype investigation.…”

Early radiation‐induced changes evaluated by intravoxel incoherent motion in the major salivary glands

“…Similarly, a few studies have recently proposed novel models to quantify or predict normal tissue radiation toxicity using functional information from FDG-PET (8), single photon emission computed tomography perfusion (34,35), and DCE-MRI (36). These studies, that propose new metrics as the metabolic dose, functional dose or bio-dose, show an emerging interest toward an innovative approach to RT that integrates into the treatment strategies the individual differences in tumor biology and radiation sensitivity of normal tissues (19)(20)(21)(22).…”

“…Currently, it is widely recognized that biological indices, reflecting patient‐specific information collected from functional imaging and/or genomics, should replace mere physical quantities, based on the dose distribution inside target volumes and normal tissues to improve the outcomes of radiation therapy . Progression in radiation biology, treatment techniques, and imaging technology supports a biologically guided radiation therapy, i.e., an adaptive radiotherapy that considers the individual differences in tumor biology and in radiation sensitivity of normal tissues to develop patient‐specific treatment strategies.…”

Radiation-induced parotid changes in oropharyngeal cancer patients: the role of early functional imaging and patient−/treatment-related factors

“…Thought the pathophysiology of parotid shrinkage during radiotherapy remains unclear [ 9 ], image-based scoring of toxicity based on early changes of irradiated organs can provide a timely, objective and consistent endpoint for patient counseling and treatment strategy adaptation [ 5 , 10 – 12 ]. In this regard, functional magnetic resonance imaging (MRI) techniques, such as diffusion- and perfusion- MRI, may have an important role, as they provide several quantitative indices strictly related to distinctive tissue signatures with radiobiological relevance, such as tissue cellular density and vascular perfusion [ 12 , 13 ].…”