Genetic predisposition to radiation-related cancer and potential implications for risk assessment

Radiation in Gastroenterology

The benefit of radiation is immense in the field of gastroenterology. Radiation is used daily in different gastrointestinal imaging and diagnostic and therapeutic interventional procedures. Radiotherapy is one of the primary modalities of treatment of gastrointestinal malignancies. There are various modalities of radiotherapy. Radiotherapy can injure malignant cells by directly damaging DNA, RNA, proteins, and lipids and indirectly by forming free radicals. External beam radiation, internal beam radiation and radio-isotope therapy are the major ways of delivering radiation to the malignant tissue. Radiation can also cause inflammation, fibrosis, organ dysfunction, and malignancy. Patients with repeated exposure to radiation for diagnostic imaging and therapeutic procedures are at slightly increased risk of malignancy. Gastrointestinal endoscopists performing fluoroscopy-guided procedures are also at increased risk of malignancy and cataract formation. The radiological protection society recommends certain preventive and protective measures to avoid side effects of radiation. Gastrointestinal complications related to radiation therapy for oncologic processes, and exposure risks for patients and health care providers involved in diagnostic or therapeutic imaging will be discussed in this review.

Radiation Reduction Strategies in Pediatric Orthopaedics

INTRODUCTION

Pediatric orthopaedic patients have the potential for significant radiation exposure from the use of imaging studies, such as computed tomography and bone scintigraphy. With the potential for long-term treatment, such as is required for scoliosis or osteogenesis imperfecta, patients are at even greater risk of radiation-induced carcinogenesis.

DISCUSSION

Although an association between radiation and cancer risk is evident, causation is difficult to prove because comorbidities or genetic predispositions may play a role in the higher baseline rates of malignancy later in life. Efforts have been made over the years to reduce exposure using more modern imaging techniques and simple radiation reduction strategies. Educational efforts and clinical practice guidelines are decreasing the rate of computed tomography scan use in pediatrics. Although considerable work is being done on the development of radiation-free imaging modalities, imaging that uses ionizing radiation will, in the near term, be necessary in specific circumstances to provide optimal care to pediatric orthopaedic patients.

CONCLUSION

Knowledge of the ionizing radiation exposure associated with commonly used tests as well as radiation-reduction strategies is essential for the optimal and safe care of pediatric orthopaedic patients.

Potential screening assays for individual radiation sensitivity and susceptibility and their current validation state

Purpose: The workshop on 'Individual Radiosensitivity and Radiosusceptibility' organized by MELODI and CONCERT on Malta in 2018, evaluated the current state of assays to identify sensitive and susceptible subgroups. The authors provide an overview on potential screening assays detecting individuals showing moderate to severe early and late radiation reactions or are at increased risk to develop cancer upon radiation exposure.Conclusion: It is necessary to separate clearly between tissue reactions and stochastic effects such as cancer when comparing the existing literature to validate various test systems. Requirements for the assays are set up. The literature is reviewed for assays that are reliable and robust. Sensitivity and specificity of the assays are regarded and scrutinized for modifying factors. Accuracy of an assay system is required to be more than 90% to balance risks of adverse reactions against risk to fail to cure the cancer. No assay/biomarker is in routine use. Assays that have shown predictive potential for radiosensitivity include SNPs, the RILA assay, and the pATM assay. A tree of risk guideline for radiologists is provided to assist medical treatment decisions. Recommendations for effective research include the setup of common retrospective and prospective cohorts/biobanks to validate current and future tests.

Novel Combined Immune Deficiency and Radiation Sensitivity Blended Phenotype in an Adult with Biallelic Variations in ZAP70 and RNF168

With the advent of high-throughput genomic sequencing techniques, novel genetic etiologies are being uncovered for previously unexplained Mendelian phenotypes, and the underlying genetic architecture of disease is being unraveled. Although most of these “mendelizing” disease traits represent phenotypes caused by single-gene defects, a percentage of patients have blended phenotypes caused by pathogenic variants in multiple genes. We describe an adult patient with susceptibility to bacterial, herpesviral, and fungal infections. Immunologic defects included CD8⁺ T cell lymphopenia, decreased T cell proliferative responses to mitogens, hypogammaglobulinemia, and radiation sensitivity. Whole-exome sequencing revealed compound heterozygous variants in ZAP70. Biallelic mutations in ZAP70 are known to produce a spectrum of immune deficiency that includes the T cell abnormalities observed in this patient. Analyses for variants in genes associated with radiation sensitivity identified the presence of a homozygous RNF168 variant of unknown significance. RNF168 deficiency causes radiosensitivity, immunodeficiency, dysmorphic features, and learning difficulties syndrome and may account for the radiation sensitivity. Thus, the patient was found to have a novel blended phenotype associated with multilocus genomic variation: i.e., separate and distinct genetic defects. These findings further illustrate the clinical utility of applying genomic testing in patients with primary immunodeficiency diseases.

Chronic myeloid leukaemia following repeated exposure to chest radiography and computed tomography in a patient with pneumothorax: A case report and literature review

It is well known that radioactive rays may cause damage to the human body. Progress in modern medicine has led to an increased risk of therapeutic and diagnostic radiation exposure of patients. Although clear evidence of a radiation dose-dependent risk of chronic myeloid leukaemia, particularly for patients exposed to radiation at a young age, has been established, it is not known whether radiation exposure during diagnostic imaging also increases the risk of cancer. The present study reports the case of a patient who underwent several diagnostic imaging tests (including repeated chest radiography and computed tomography) for recurrent pneumothorax. At around one year subsequent to these tests, the patient was diagnosed with chronic myeloid leukaemia. The patient exhibited an increase in white blood cell count over time, and a bone marrow smear test showed a myeloid/erythroid ratio of 13.9:1. In addition, the qualitative breakpoint cluster region (BCR)/Abelson (ABL) gene test revealed positive results for BCR/ABL fusion (p210). Based on the data reported in the current case, research aimed at elucidating the potential risks associated with diagnostic radiation is urgently required. It is crucial that medical professionals consider the potential harmful side effects of diagnostic radiation when ordering radiation-based diagnostic imaging examinations.