Risk Of Radiation-associated Cancer Research Articles

Cohort profile: ORICAMs, a French cohort of medical workers exposed to low-dose ionizing radiation.

Medical personnel represent the largest group of workers occupationally exposed to ionizing radiation. Although the health risks associated with occupational exposure to low doses of ionizing radiation in the medical field have been investigated in several national cohorts, no study has been conducted in France to date. The ORICAMs (Occupational Radiation Induced Cancer in Medical staff) cohort is a nationwide French longitudinal cohort of medical workers exposed to ionizing radiation aiming to investigate the risk of radiation-associated cancer and non-cancer mortality. The ORICAMs cohort was set up in 2011 and includes all medical personnel monitored for ionizing radiation exposure with at least one dosimetric record in the SISERI database (the national registry for monitoring ionizing radiation exposure in workers) over the period 2002-2012. Causes of death were abstracted from death certificates and coded according to ICD-10. The follow-up ended on 31/12/2013. Standardized mortality ratios (SMRs) were calculated by cause of death to compare the mortality in the cohort to that in the French population, by gender, age group and calendar period. Among the 164,015 workers included in the cohort (60% women) a total of 1,358 deaths (892 in male and 466 in female) were reported. The observed number of all-cause deaths was significantly lower than expected based on national rates in both male (SMR = 0.35; 95% CI: 0.33, 0.38; ndeaths = 892) and female (SMR = 0.41; 95% CI: 0.38, 0.45; ndeaths = 466). This analysis leads to the conclusion that mortality in French workers exposed to medical radiation is significantly lower than the national reference rates. However, these results based on a comparative analysis with national rates may be impacted by the healthy worker effect towards low SMRs, and do not enable to establish a potential relationship between occupational exposure and mortality risk, even if we may suspect an impact of high SES of these professionals on the observed decreased mortality. Thus, further dose-response analyses based on individual ionizing radiation exposure and job's type will be conducted to characterize correlation between risk of cancer mortality and occupational exposure.

Exposure to low-dose ionizing radiation from cardiac catheterization and risk of cancer: the COCCINELLE study

The COCCINELLE study is a nationwide retrospective French cohort set up to evaluate the risk of radiation associated cancer in patients who undergone cardiac catheterization (CC) procedures for diagnosis or treatment of congenital heart disease during childhood [1] . Children who undergone CC procedures from 01/01/2000 to 31/12/2013 before the age of 16 in one of the 15 pediatric cardiology departments which perform pediatric CC in mainland France were included. The follow-up started at the date of the first recorded CC procedure until the exit date, i.e. the date of death, the date of first cancer diagnosis, the date of the 18 th birthday, or the 31/12/2015, whichever occurred first. The cohort was linked to the National Childhood Cancer Registry to identify patients diagnosed with cancer and with the French National Directory for the Identification of Natural Persons to retrieve the patients’ vital status. An external comparison was conducted using standardized incidence ratios (SIR). Breslow and Day's approximation was used to estimate 95% confidence intervals (CI) for the SIRs [2] . A total of 17,104 children were included in the cohort and followed for 110,335 person-years, with 22,227 CC procedures collected. Among the patients, 81.6% received only one procedure. Fifty-nine cancer cases were observed in the cohort. SIRs were increased for all-cancer (SIR = 3.8, 95% CI 2.9, 4.9), leukemia (SIR = 3.3, 95% CI 2.0, 5.4), lymphoma (SIR = 14.9, 95% CI 9.9, 22.5) and solid cancers excluding central nervous system tumors (SIR = 3.3, 95% CI 2.0, 5.5) compared with the general population. Increased risks of cancer were observed. Potential explanations include shared genetic or environmental factors, immunosuppression drugs, and exposure to medical ionizing radiation procedures. The dose-response analysis between ionizing radiation doses received during CCs and cancer occurrence will allow to address this question.

Justification and Optimization Principles of ALARA in Pediatric CT at a Teaching Hospital in Ethiopia.

Radiation from CT (computerized tomography), poses risk of radiation associated cancer. Studies indicate a cumulative dose of 50mGy triples the risk of leukemia and a dose of 60mGy triples the risk of brain tumors in children. This study aimed to assess the application of "Justification and Optimization Principles of ALARA (As Low As Reasonably Achievable)" in pediatric CT. A prospective cross-sectional study was conducted from December 2017 to July 2018 G.C at Tikur Anbessa Specialized Hospital. CT request forms were reviewed. All pediatric patients listed for CT were included. The collected data were analyzed using SPSS version 25. Four hundred and twenty nine CT requests were reviewed, 246 (57.3%) were males and 183(42.7%) were females; 52(12.1%) were less than 1 year old, 153(35.7%) between 1 to 5 years, 113(26.3%) between 5 to 10 years and 111(25.8%) 10 to 14 years old. On the other hand, 28(6.5%) scan requests were rejected based on the ALARA justification principle, and from these, in 11(39.2%) MRI was recommended instead of CT, in 6(21.42%) US was recommended. Review of previous CT helped to reject 4(14.28%). Review of prior chest radiographs helped in rejecting 2(7.14%) requests. For 5(17.8%) and 19(4.4%), requests were optimized by applying principles of optimization to reduce received dose from CT. Overall, 47(11%) patients were protected from unnecessary radiation exposure by applying the principles of ALARA. The use of other alternating imaging modalities is vital in pediatric patients who are more radiosensitive and have longer time to manifest radiation induced injury.

Computed tomography rates and estimated radiation-associated cancer risk among injured children treated at different trauma center types

BackgroundTrauma is a common indication for computed tomography (CT) in children. However, children are particularly vulnerable to CT radiation and its associated cancer risk. Identifying differences in CT usage across trauma centers and among specific populations of injured children is needed to identify where quality improvement initiatives could be implemented in order to reduce excess radiation exposure to children. We evaluated computed tomography (CT) rates among injured children treated at pediatric (PTC), mixed (MTC), or adult trauma centers (ATC) and estimated the resulting differential in potential cancer risk. MethodsWe identified children age ≤18 years with blunt injury AIS ≥2 treated from 2010 to 2013 at 130 U.S trauma centers participating in the Trauma Quality Improvement Program. CT rates were compared across center types using Chi-square analysis. Stratified analyses in children with varying injury severity, mechanism, and age were performed. We estimated the impact of differential rates of CT scans on cancer risk using published attributable risks. ResultsAmong 59,010 children identified, CT rates were higher among injured children treated at ATC and MTC versus PTC. Findings were consistent after stratified analyses and were most striking in children with chest and abdomen/pelvis CT, adolescent age, low injury severity and fall injury mechanism. We estimated that for every 100,000 injured children, imaging practices in ATC and MTC would lead to an additional 17 and 16 lifetime cancers, respectively, when compared to PTC. ConclusionCT use among injured children is higher at ATC and MTC compared to PTC. Children with low injury severity, fall injury mechanism, and adolescent age are most vulnerable to differential imaging practices across centers. Quality improvement initiatives aimed at reducing heterogeneity in CT usage across trauma centers are required to mitigate pediatric radiation exposure and cancer risk.

In vivo dosimetry for head ct examinations in paediatric patients

Introduction Serious concerns about children exposure to ionizing radiation have been raised due to the widespread use of computed tomography (CT) in paediatrics. The increased radiosensitivity of children and the radiation-associated cancer risk call for immediate action in the field of patient-specific dosimetry and optimization of existing CT protocols. Purpose The main objective of our study is to present in vivo radiation dose measurements during paediatric head CT examinations using thermoluminescent dosimeters (TLDs). To our knowledge, there are limited literature data concerning in vivo dosimetry in paediatric patients. Materials and methods The ongoing study includes paediatric patients ranging from neonates to 15 years old who underwent head CT examinations on a 16-slice CT scanner in ‘’Agia Sofia” Children’s Hospital in Athens using iterative reconstruction algorithm. LiF:Cu,P TLDs, properly calibrated, were placed in eyes, forehead, behind ears and thyroid glands. Surface doses to the lens of the eye, the brain and the thyroid were calculated for each patient. Results For patients ⩽5 years old, surface doses in eye lens, brain and thyroids were 38.45 ± 5 mGy, 33.69 ± 14.05 mGy and 1.84 ± 0.48 mGy respectively, while for patients >5 years old, the surface doses were 35.56 ± 11.16 mGy, 40.04 ± 7.67 mGy and 2.05 ± 0.32 mGy respectively. Conclusion Although there are many challenges, patient-specific dosimetry is of great importance in paediatric patients. In vivo dosimetry is a powerful tool which provides an accurate and effective method for skin dose measurements. Furthermore, since the eyes and the thyroid are superficial organs, the calculated surface dose can give a good estimation of the organ dose to ocular lens and thyroid gland. Disclosure None.

Post-crisis efforts towards recovery and resilience after the Fukushima Daiichi Nuclear Power Plant accident.

One of the well-known radiation-associated late-onset cancers is childhood thyroid cancer as demonstrated around Chernobyl apparently from 1991. Therefore, immediately after the Fukushima Daiichi Nuclear Power Plant accident on March 2011, iodine thyroid blocking was considered regardless of its successful implementation or not at the indicated timing and places as one of the radiation protection measurements, in addition to evacuation and indoor sheltering, because a short-lived radioactive iodine was massively released into the environment which might crucially affect thyroid glands through inhalation and unrestricted consumption of contaminated food and milk. However, very fortunately, it is now increasingly believed that the exposure doses on the thyroid as well as whole body are too low to detect any radiation-associated cancer risk in Fukushima. Although the risk of radiation-associated health consequences of residents in Fukushima is quite different from that of Chernobyl and is considerably low based on the estimated radiation doses received during the accident for individuals, a large number of people have received psychosocial and mental stresses aggravated by radiation fear and anxiety, and remained in indeterminate and uncertain situation having been evacuated but not relocated. It is, therefore, critically important that best activities and practices related to recovery and resilience should be encouraged, supported and implemented at local and regional levels. Since psychosocial well-being of individuals and communities is the core element of resilience, local individuals, health professionals and authorities are uniquely positioned to identify and provide insight into what would provide the best resolution for their specific needs.

Impact on the Japanese Atomic Bomb Survivors of Radiation Received From the Bombs

The Radiation Effects Research Foundation (RERF) studies various cohorts of Japanese atomic bomb survivors, the largest being the Life Span Study (LSS), which includes 93,741 persons who were in Hiroshima or Nagasaki at the times of the bombings; there are also cohorts of persons who were exposed in utero and survivors' children. This presentation attempts to summarize the total impact of the radiation from the bombs on the survivors from both an individual perspective (both age-specific and integrated lifetime risk, along with a measure of life expectancy that describes how the risk affects the individual given age at exposure) and a group perspective (estimated numbers of excess occurrences in the cohort), including both early and late effects. As survivors' doses ranged well into the acutely lethal range at closer distances, some of them experienced acute signs and symptoms of radiation exposure in addition to being at risk of late effects. Although cancer has always been a primary concern among late effects, estimated numbers of excess cancers and hematopoietic malignancies in the LSS are a small fraction of the total due to the highly skewed dose distribution, with most survivors receiving small doses. For example, in the latest report on cancer incidence, 853 of 17,448 incident solid cancers were estimated to be attributable to radiation from the bombs. RERF research indicates that risk of radiation-associated cancer varies among sites and that some benign tumors such as uterine myoma are also associated with radiation. Noncancer late effects appear to be in excess in proportion to radiation dose but with an excess relative risk about one-third that of solid cancer and a correspondingly small overall fraction of cases attributable to radiation. Specific risks were found for some subcategories, particularly circulatory disease, including stroke and precedent conditions such as hypertension. Radiation-related cataract in the atomic bomb survivors is well known, with evidence in recent years of risk at lower dose levels than previously appreciated. In addition to somatic effects, survivors experienced psychosocial effects such as uncertainty, social stigma, or rejection, and other social pressures. Developmental deficits associated with in utero exposure, notably cognitive impairment, have also been described. Interaction of radiation with other risk factors has been demonstrated in relation to both cancer and noncancer diseases. Current research interests include whether radiation increases risk of diabetes or conditions of the eye apart from cataract, and there continues to be keen interest as to whether there are heritable effects in survivors' children, despite negative findings to date. Introduction of Impact on the Japanese Atomic- Bomb Survivors (Video 1:52, http://links.lww.com/HP/A29).

Secondary Carcinogenesis in Patients Treated with Radiation: A Review of Data on Radiation-Induced Cancers in Human, Non-human Primate, Canine and Rodent Subjects

Concern for risk of radiation-induced cancer is growing with the increasing number of cancer patients surviving long term. This study examined data on radiation transformation of mammalian cells in vitro and on the risk of an increased cancer incidence after irradiation of mice, dogs, monkeys, atomic bomb survivors, occupationally exposed persons, and patients treated with radiation. Transformation of cells lines in vitro increased linearly with dose from approximately 1 to approximately 4-5 Gy. At <0.1 Gy, transformation was not increased in all studies. Dose-response relationships for cancer incidence varied with mouse strain, gender and tissue/organ. Risk of cancer in Macaca mulatta was not raised at 0.25-2.8 Gy. From the atomic bomb survivor study, risk is accepted as increasing linearly to 2 Sv for establishing exposure standards. In irradiated patients, risk of cancer increased significantly from 1 to 45 Gy (a low to a high dose level) for stomach and pancreas, but not for bladder and rectum (1-60 Gy) or kidney (1-15 Gy). Risk for several organs/tissues increased substantially at doses far above 2 Gy. There is great heterogeneity in risk of radiation-associated cancer between species, strains of a species, and organs within a species. At present, the heterogeneity between and within patient populations of virtually every parameter considered in risk estimation results in substantial uncertainty in quantification of a general risk factor. An implication of this review is that reduced risks of secondary cancer should be achieved by any technique that achieved a dose reduction down to approximately [corrected] 0.1 Gy, i.e. dose to tissues distant from the target. The proportionate gain should be greatest for dose decrement to less than 2 Gy.

WE‐C‐224A‐02: Radiation Induced Cancers in Treated Patients

The increasing numbers of radiation treated patient surviving for long periods forces an assessment of their risk of radiation associated cancer. Dose response relationships for cancer induction in the laboratory mice varies with strain, gender, tissue/organ of concern, observation period, dose fractionation and LET. For most experiments, risk increased with dose in an orderly manner. However, in some large experiments on mice and one on Macaca mullata, there was no evident increase risk of cancer at 1–2.Gy single dose WBI. These studies were life span and autopsy examinations.Risk of death due radiation induced solid cancer among 86,611 survivors of the atom bomb explosions in 1945 [entered the study in 1950] increased throughout the observation period of 52 years. There have been 10,127 deaths due to solid cancer and of these, 479 [4.7%] have been attributed to the radiation exposure. The time distribution of these cancer deaths have been: 18%, 19.1%, 27.1% and 35.4 % for the periods 1950–67, 1968–77, 1978–87 and 1988–97. Namely, 35% of these radiation cancer deaths occurred at 42–52 years post irradiation.Data from 14 large and long follow‐up series of irradiated human patients demonstrate increased risk with dose for cancers of the stomach and pancreas; over the dose range 1–45 Gy. In contrast there was no evident increased risk of bladder or rectal cancer after doses of 1–60 Gy. For the studies on murine, canine, sub‐human and human subjects there is not a constant relative risk for the different organs, viz probability of a radiation cancer for a specified dose varies with the organ.Consideration will be given to the differential risk between photon [conformal and IMXT], proton [broad beam energy modulated and pencil beam scattered] and 12C ion beams.

Radiation Risks Potentially Associated with Low-Dose CT Screening of Adult Smokers for Lung Cancer

To estimate the radiation-related lung cancer risks associated with annual low-dose computed tomographic (CT) lung screening in adult smokers and former smokers, and to establish a baseline risk that the potential benefits of such screening should exceed. The estimated lung radiation dose from low-dose CT lung examinations corresponds to a dose range for which there is direct evidence of increased cancer risk in atomic bomb survivors. Estimated dose-, sex-, and smoking status-dependent excess relative risks of lung cancer were derived from cancer incidence data for atomic bomb survivors and used to calculate the excess lung cancer risks associated with a single CT lung examination at a given age in a U.S. population. From these, the overall radiation risks associated with annual CT lung screening were estimated. A 50-year-old female smoker who undergoes annual CT lung screening until age 75 would incur an estimated radiation-related lung cancer risk of 0.85%, in addition to her otherwise expected lung cancer risk of approximately 17%. The radiation-associated cancer risk to other organs would be far lower. If 50% of all current and former smokers in the U.S. population aged 50-75 years received annual CT screening, the estimated number of lung cancers associated with radiation from screening would be approximately 36,000, a 1.8% (95% credibility interval: 0.5%, 5.5%) increase over the otherwise expected number. Given the estimated upper limit of a 5.5% increase in lung cancer risk attributable to annual CT-related radiation exposure, a mortality benefit of considerably more than 5% may be necessary to outweigh the potential radiation risks.

Cost-effectiveness in nuclear medicine

There are many pressures on nuclear medicine physicians to keep costs down and to produce the most efficacious results for the money spent. A procedure is cost-effective if its benefits (correct diagnosis, effective treatment, etc.) are worth the additional costs (money, radiation dose, etc.). The benefits of diagnostic procedures are measured by test performance (diagnostic efficacy [efficacy-D]), which in turn depends on a specific task: detection, classification, localization, or quantitation. For the detection task, measures of test performance include sensitivity, specificity, predictive value, accuracy, diagnostic utility, posttest versus pretest disease probability, area under a receiver operating characteristic (ROC) curve, and others. Standard measures of test performance in the classification, localization, and quantitation tasks have not yet been developed. Efficacy-M (management efficacy) is a measure of the extent to which a procedure influences patient management appropriately. Efficacy-O (outcome efficacy) is a measure of the success of therapeutic procedures. Some publications illustrating these points are presented. Costs associated with nuclear medicine procedures include money, time, discomfort, possible drug reactions, radiation dose, and the hypothetical risk of radiation-associated cancer. The public's perception of these latter risks, or costs, is much higher than our knowledge would justify. Decision trees are useful for laying out all possible strategies, outcomes, costs, and benefits, and estimating the cost-effectiveness of each strategy. Some articles estimating cost-effectiveness in nuclear medicine are reviewed, although few articles in the literature make any detailed use of decision analysis. Much work remains to be done in forming a coherent, consistent procedure for assessing cost-effectiveness in nuclear medicine.