Technological developments have allowed improvements in radiotherapy delivery, with higher precision and better sparing of normal tissue. For many years, it has been well known that ionizing radiation has not only local action but also systemic effects by triggering many molecular signaling pathways. There is still a lack of knowledge of this issue. This review focuses on the current literature about the effects of ionizing radiation on the immune system, either suppressing or stimulating the host reactions against the tumor, and the factors that interact with these responses, such as the radiation dose and dose / fraction effects in the tumor microenvironment and vasculature. In addition, some implications of these effects in cancer treatment, mainly in combined strategies, are addressed from the perspective of their interactions with the more advanced technology currently available, such as heavy ion therapy and nanotechnology.

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This study evaluated the efficacy of low-level laser therapy (LLLT) and aluminum hydroxide (AH) in the prevention of oral mucositis (OM). A prospective, comparative and non-randomized study was conducted with 25 patients with head and neck cancer subjected to radiotherapy (RT) or radiochemotherapy (RCT). Twelve patients received LLLT (830 nm, 15 mW, 12 J/cm²) daily from the 1st day until the end of RT before each sessions during 5 consecutive days, and the other 13 patients received AH 310 mg/5 mL, 4 times/day, also throughout the duration of RT, including weekends. OM was measured using an oral toxicity scale (OTS) and pain was measured using the visual analogue scale (VAS). EORTC questionnaires were administered to the evaluate impact of OM on quality of life. The LLLT group showed lower mean OTS and VAS scores during the course of RT. A significant difference was observed in pain evaluation in the 13th RT session (p=0.036). In both groups, no interruption of RT was needed. The prophylactic use of both treatments proposed in this study seems to reduce the incidence of severe OM lesions. However, the LLLT was more effective in delaying the appearance of severe OM.

Background/Objectives: The practice of palliative radiation therapy (RT) is based on extrapolation from adult literature. We evaluated patterns of pediatric palliative RT to describe regimens used to identify opportunity for future pediatric-specific clinical trials. Results: Of 3,225 pediatric patients, 365 (11%) were treated with palliative intent to a total of 427 disease sites. Anesthesia was required in 10% of patients. Treatment was delivered to metastatic disease in 54% of patients. Histologies included neuroblastoma (30%), osteosarcoma (18%), leukemia/lymphoma (12%), rhabdomyosarcoma (12%), medulloblastoma/ependymoma (12%), Ewing sarcoma (8%), and other (8%). Indications included pain (43%), intracranial symptoms (23%), respiratory compromise (14%), cord compression (8%), and abdominal distention (6%).Sites included nonspine bone (35%), brain (16% primary tumors, 6% metastases), abdomen/pelvis (15%), spine (12%), head/neck (9%), and lung/mediastinum (5%). Re-irradiation comprised 16% of cases. Techniques employed three-dimensional conformal RT (41%), intensity-modulated RT (23%), conventional RT (26%), stereotactic body RT (6%), protons (1%), electrons (1%), and other (2%). The most common physician-reported barrier to consideration of palliative RT was the concern about treatment toxicity (83%). Conclusion:There is significant diversity of practice in pediatric palliative RT. Combined with ongoing research characterizing treatment response and toxicity, these data will inform the design of forthcoming clinical trials to establish effective regimens and minimize treatment toxicity for this patient population. K E Y W O R D Spalliative radiation therapy, palliative therapy, pediatric radiation therapy Abbreviations: RT, radiation therapy; SBRT, stereotactic body radiation therapy

Use of IGRT in children was prevalent at all consortium institutions. There was treatment site-specific variability in IGRT use and technique across institutions, although practices varied less at proton facilities. Despite use of IGRT, there was no consensus of optimum PTV margin by treatment site. Given the desire to restrict any additional radiation exposure in children to instances where the exposure is associated with measureable benefit, prospective studies are warranted to optimize IGRT protocols by modality and treatment site.