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Biomedical subjects

E Ron

Publications and source records attributed to E Ron.

At least 19 recordsLinked to original sources
PubMed2006

Autoimmune thyroiditis and exposure to iodine 131 in the Ukrainian cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: results from the first screening cycle (1998-2000).

CONTEXT: Due to the Chornobyl accident, millions were exposed to radioactive isotopes of iodine and some received appreciable iodine 131 (131I) doses. A subsequent increase in thyroid cancer has been largely attributed to this exposure, but evidence concerning autoimmune thyroiditis (AIT) remains inconclusive. OBJECTIVE: The objective of the study was to quantify risk of AIT after 131I exposure. DESIGN/SETTING/PARTICIPANTS: Baseline data were collected from the first screening cycle (1998-2000) of a large cohort of radiation-exposed individuals (n = 12,240), residents of contaminated, iodine-deficient territories of Ukraine. Study individuals were under the age of 18 yr on April 26, 1986, and had thyroid radioactivity measurements made shortly after the accident. OUTCOMES: AIT was defined a priori based on various combinations of elevated antibodies to thyroid peroxidase (ATPO), TSH, and clinical findings; elevated ATPO were considered to be an indicator of thyroid autoimmunity. RESULTS: No significant association was found between 131I thyroid dose estimates and AIT, but prevalence of elevated ATPO demonstrated a modest, significant association with 131I that was well described by several concave models. This relationship was apparent in individuals with moderately elevated ATPO and euthyroid, thyroid disease-free individuals. CONCLUSIONS: Twelve to 14 yr after the Chornobyl accident, no radiation-related increase in prevalence of AIT was found in a large cohort study, the first in which 131I thyroid doses were estimated using individual radioactivity measurements. However, a dose-response relationship with ATPO prevalence raises the possibility that clinically important changes may occur over time. Thus, further follow-up and analysis of prospective data in this cohort are necessary.

Adolescent↗
PubMed2006

Body mass index and all-cause mortality in a nationwide US cohort.

OBJECTIVE: To investigate whether the nature of the relationship between body mass index (BMI (kg/m2)) and all-cause mortality is direct, J- or U-shaped, and whether this relationship changes as people age. DESIGN: Prospective nationwide cohort study of US radiologic technologists (USRT). SUBJECTS: Sixty-four thousand seven hundred and thirty-three female and 19 011 male certified radiation technologists. METHODS: We prospectively followed participants from the USRT study who completed a mail survey in 1983-1989 through 2000. During an average of 14.7 years of follow-up or 1.23 million person-years, 2278 women and 1495 men died. Using Cox's proportional-hazards regression analyses, we analyzed the relationship between BMI and all-cause mortality by gender and by age group (<55 years; > or = 55 years). We also examined risk in never-smokers after the first 5 years of follow-up to limit bias owing to the confounding effects of smoking and illness-related weight loss on BMI and mortality. RESULTS: Risks were generally J-shaped for both genders and age groups. When we excluded smokers and the first 5 year of follow-up, risks were substantially reduced in those with low BMIs. In never-smoking women under the age of 55 years (excluding the initial 5-year follow-up period), risk rose as BMI increased above 21.0 kg/m2, whereas in older women, risk increased beginning at a higher BMI (> or = 25.0 kg/m2). Among younger men who never smoked (excluding the initial 5-year follow-up period), risk began to rise above a BMI of 23.0 kg/m2, whereas in older men, risk did not begin to increase until exceeding a BMI of 30.0 kg/m2. CONCLUSIONS: In younger/middle-aged, but not older, women and men, mortality risks appear directly related to BMI. The more complicated relationship between BMI and mortality in older subjects suggests the importance of assessing whether other markers of body composition better explain mortality risk in older adults.

Adult↗
PubMed2006

Thyroid abnormalities associated with protracted childhood exposure to 131I from atmospheric emissions from the Mayak weapons facility in Russia.

Between 1948 and 1960, the Mayak nuclear weapons facility in Ozyorsk, Russia discharged relatively high levels of radionuclides, primarily (131)I, into the atmosphere, resulting in appreciable exposure to the residents of Ozyorsk. To evaluate the association between thyroid diseases and childhood exposure to radioiodines, we screened 894 Ozyorsk residents born between 1952 and 1953. The study population was comprised of 581 exposed individuals living in Ozyorsk during the years of heaviest exposure and 313 nonexposed individuals who moved to Ozyorsk when radiation exposure from Mayak largely had ended. The screening protocol included a patient interview, palpation of the thyroid, cervical lymph nodes and salivary glands, an ultrasound examination, and measurement of fT4, TSH and TPOAb. Twenty-eight percent of the study group was diagnosed with a thyroid abnormality. The prevalence of nodular disease was significantly higher in the exposed group (20.7%) compared with the nonexposed (14.4%) group (relative risk = 1.4, 95% CI = 1.1; 1.9). Risks were larger for solitary nodules and for nodules > or = 10 mm in diameter. Expansion of the study to increase the number of persons screened as well as detailed dose estimation would offer an unique opportunity to evaluate thyroid disease in relation to chronic exposure to radioiodines during childhood.

Adolescent↗
PubMed2006

Normal organ radiation dosimetry and associated uncertainties in nuclear medicine, with emphasis on iodine-131.

In many medical applications involving the administration of iodine-131 ((131)I) in the form of iodide (I(-)), most of the dose is delivered to the thyroid gland. To reliably estimate the thyroid absorbed dose, the following data are required: the thyroid gland size (i.e. mass), the fractional uptake of (131)I by the thyroid, the spatial distribution of (131)I within the thyroid, and the length of time (131)I is retained in the thyroid before it is released back to blood, distributed in other organs and tissues, and excreted from the body. Estimation of absorbed dose to nonthyroid tissues likewise requires knowledge of the time course of activity in each organ. Such data are rarely available, however, and therefore dose calculations are generally based on reference models. The MIRD and ICRP have published metabolic models and have calculated absorbed doses per unit intake for many nuclides and radioactive pharmaceuticals. Given the activity taken into the body, one can use such models and make reasonable calculations for average organ doses. When normal retention and excretion pathways are altered, the baseline models need to be modified, and the resulting organ dose estimates are subject to larger errors. This paper describes the historical evolution of radioactive isotopes in medical diagnosis and therapy. We nonmathematically summarize the methods used in current practice to estimate absorbed dose and summarize some of the risk data that have emerged from medical studies of patients with special attention to dose and effects observed in those who received (131)I-iodide in diagnosis and/or therapy.

Body Burden↗
PubMed2006

Post-Chernobyl thyroid cancers in Ukraine. Report 2: risk analysis.

On April 26, 1986, the worst nuclear reactor accident to date occurred at the Chornobyl (Chernobyl) power plant in Ukraine. Millions of people in Ukraine, Belarus and Russia were exposed to radioactive nuclides, especially (131)I. Since then, research has been conducted on various subgroups of the exposed population, and it has been demonstrated that the large increase in thyroid cancer is related to the (131)I exposure. However, because of study limitations, quantified risk estimates are limited, and there remains a need for additional information. We conducted an ecological study to investigate the relationship between (131)I thyroid dose and the diagnosis of thyroid cancer in three highly contaminated oblasts in Northern Ukraine. The study population is comprised of 301,907 persons who were between the ages of 1 and 18 at the time of the Chornobyl accident and were living in 1,293 rural settlements in the three study oblasts. Twenty-four percent of the study population had individual thyroid dose estimates and the other 76% had "individualized" estimates of thyroid dose based on direct thyroid measurements taken from a person of the same age and gender living in the same or nearby settlement. Cases include 232 thyroid cancers diagnosed from January 1990 through December 2001, and all were confirmed histologically. Dose-response analyses took into account differences in the rate of ultrasound examinations conducted in the three study oblasts. The estimated excess relative risk per gray was 8.0 (95% CI = 4.6-15) and the excess absolute risk per 10,000 person-year gray was estimated to be 1.5 (95% CI = 1.2-1.9). In broad terms, these estimates are compatible with results of other studies from the contaminated areas, as well as studies of external radiation exposure.

Adolescent↗
PubMed2005

Incidence of haematopoietic malignancies in US radiologic technologists.

BACKGROUND: There are limited data on risks of haematopoietic malignancies associated with protracted low-to-moderate dose radiation. AIMS: To contribute the first incidence risk estimates for haematopoietic malignancies in relation to work history, procedures, practices, and protective measures in a large population of mostly female medical radiation workers. METHODS: The investigators followed up 71,894 (77.9% female) US radiologic technologists, first certified during 1926-80, from completion of a baseline questionnaire (1983-89) to return of a second questionnaire (1994-98), diagnosis of a first cancer, death, or 31 August 1998 (731,306 person-years), whichever occurred first. Cox proportional hazards regression was used to compute risks. RESULTS: Relative risks (RR) for leukaemias other than chronic lymphocytic leukaemia (non-CLL, 41 cases) were increased among technologists working five or more years before 1950 (RR = 6.6, 95% CI 1.0 to 41.9, based on seven cases) or holding patients 50 or more times for x ray examination (RR = 2.6, 95% CI 1.3 to 5.4). Risks of non-CLL leukaemias were not significantly related to the number of years subjects worked in more recent periods, the year or age first worked, the total years worked, specific procedures or equipment used, or personal radiotherapy. Working as a radiologic technologist was not significantly linked with risk of multiple myeloma (28 cases), non-Hodgkin's lymphoma (118 cases), Hodgkin's lymphoma (31 cases), or chronic lymphocytic leukaemia (23 cases). CONCLUSION: Similar to results for single acute dose and fractionated high dose radiation exposures, there was increased risk for non-CLL leukaemias decades after initial protracted radiation exposure that likely cumulated to low-to-moderate doses.

Adult↗
PubMed2005

The Techa River Cohort: study design and follow-up methods.

Residents living on the banks of the Techa River in the Southern Urals region of Russia were exposed to radioactive contamination from the Mayak plutonium production and separation facility that discharged liquid radioactive waste into this river. This paper describes the methods used to establish and follow the Extended Techa River Cohort (ETRC), which includes almost 30,000 people living along the Techa River who were exposed to a complex mixture of radionuclides, largely 90Sr and 137Cs. The system of regular follow-up allows ascertainment of vital status, cause of death and cancer incidence. With over 50 years of follow-up and over 50% deceased, the ETRC now provides a valuable opportunity to study a wide range of health effects, both early and late, associated with protracted internal and external radiation exposures. The wide range of doses allows analysis of the nature of the dose-response relationship based on internal comparisons. Other features of the cohort are the high proportion (40%) exposed under age 20, and the inclusion of both sexes. The limitations of the study include loss to follow-up due to difficulties in tracing some cohort members and migration and incomplete ascertainment of cause of death.

Adult↗
PubMed2005

Protracted radiation exposure and cancer mortality in the Techa River Cohort.

In the 1950s many thousands of people living in rural villages on the Techa River received protracted internal and external exposures to ionizing radiation from the release of radioactive material from the Mayak plutonium production complex. The Extended Techa River Cohort includes 29,873 people born before 1950 who lived near the river sometime between 1950 and 1960. Vital status and cause of death are known for most cohort members. Individualized dose estimates have been computed using the Techa River Dosimetry System 2000. The analyses provide strong evidence of long-term carcinogenic effects of protracted low-dose-rate exposures; however, the risk estimates must be interpreted with caution because of uncertainties in the dose estimates. We provide preliminary radiation risk estimates for cancer mortality based on 1,842 solid cancer deaths (excluding bone cancer) and 61 deaths from leukemia. The excess relative risk per gray for solid cancer is 0.92 (95% CI 0.2; 1.7), while those for leukemia, including and excluding chronic lymphocytic leukemia, are 4.2 (CI 95% 1.2; 13) and 6.5 (CI 95% 1.8; 24), respectively. It is estimated that about 2.5% of the solid cancer deaths and 63% of the leukemia deaths are associated with the radiation exposure.

Cohort Studies↗
PubMed2004

Lung cancer in Mayak workers.

The cohort of nuclear workers at the Mayak Production Association, located in the Russian Federation, is a unique resource for providing information on the health effects of exposure to plutonium as well as the effects of protracted external dose. Lung cancer mortality risks were evaluated in 21,790 Mayak workers, a much larger group than included in previous evaluations of lung cancer risks in this cohort. These analyses, which included 655 lung cancer deaths occurring in the period 1955-2000, were the first to evaluate both excess relative risk (ERR) and excess absolute risk (EAR) models and to give detailed attention to the modifying effects of gender, attained age and age at hire. Lung cancer risks were found to be significantly related to both internal dose to the lung from plutonium and external dose, and risks were described adequately by linear functions. For internal dose, the ERR per gray for females was about four times higher than that for males, whereas the EAR for females was less than half that for males; the ERR showed a strong decline with attained age, whereas the EAR increased with attained age until about age 65 and then decreased. Parallel analyses of lung cancer mortality risks in Mayak workers and Japanese A-bomb survivors were also conducted. Efforts currently under way to improve both internal and external dose estimates, and to develop data on smoking, should result in more accurate risk estimates in the future.

Adolescent↗
PubMed2003

Dose response and temporal patterns of radiation-associated solid cancer risks.

Findings of the Life Span Study (LSS) cohort of atomic-bomb survivors are a primary source for quantitative risk estimates that underlie radiation protection. Because of the size and length of follow-up, the LSS provides considerable information on both the nature of the dose response and on how radiation-associated excess risks vary with age, age at exposure, sex, and other factors. Our current analyses extend the mortality follow-up by 7 y (through 1997) and add 8 y (through 1995) to the incidence follow-up. During the follow-up periods there have been a total of about 9,300 solid cancer deaths and almost 12,200 incident cases. As outlined in this presentation, while discussing issues related to the shape of the dose response and low dose risks in some detail, the new reports consider temporal patterns in greater detail than has been done previously. As we have reported, the LSS solid cancer dose response is well described by simple linear dose response over the 0 to 2 Sv range (with some leveling off at higher estimated doses). This remains the case with the extended follow-up. Although LSS is often referred to as a high dose study, about 75% of the 50,000 cohort members with doses in excess of 5 mSv have dose estimates in a range of direct interest for radiation protection (0-200 mSv). Analyses of data limited to this low dose range provide direct evidence of a significant solid cancer dose response with a risk per unit dose that is consistent with that seen for the full dose range. Previous LSS reports have focused on descriptions of the solid cancer excess risks in which the excess relative risk varies with age at exposure and sex. In addition to the age at exposure effects, our current analyses suggest excess relative risks also vary with age (at death or diagnosis). Excess relative risks are higher for those exposed earlier in life, with attained age-specific risks changing by about 20% per decade, but tend to decrease with increasing attained age, roughly in proportion to (1/attained-age)1.5, for any age at exposure. Despite the decreasing relative risk, excess rates have increased rapidly throughout the study period with some indication, especially for the incidence data, that attained-age-specific rates are higher for those exposed at younger ages. Simple comparisons of site-specific excess risks are used to illustrate how the interpretation of age-at-exposure effects on excess relative risks or excess rates is complicated by changes in baseline rates with birth cohort or time period.

Age Factors↗
PubMed2003

Cancer mortality risk among workers at the Mayak nuclear complex.

At present, direct data on risk from protracted or fractionated radiation exposure at low dose rates have been limited largely to studies of populations exposed to low cumulative doses with resulting low statistical power. We evaluated the cancer risks associated with protracted exposure to external whole-body gamma radiation at high cumulative doses (the average dose is 0.8 Gy and the highest doses exceed 10 Gy) in Russian nuclear workers. Cancer deaths in a cohort of about 21,500 nuclear workers who began working at the Mayak complex between 1948 and 1972 were ascertained from death certificates and autopsy reports with follow-up through December 1997. Excess relative risk models were used to estimate solid cancer and leukemia risks associated with external gamma-radiation dose with adjustment for effects of plutonium exposures. Both solid cancer and leukemia death rates increased significantly with increasing gamma-ray dose (P < 0.001). Under a linear dose-response model, the excess relative risk for lung, liver and skeletal cancers as a group (668 deaths) adjusted for plutonium exposure is 0.30 per gray (P < 0.001) and 0.08 per gray (P < 0.001) for all other solid cancers (1062 deaths). The solid cancer dose-response functions appear to be nonlinear, with the excess risk estimates at doses of less than 3 Gy being about twice those predicted by the linear model. Plutonium exposure was associated with increased risks both for lung, liver and skeletal cancers (the sites of primary plutonium deposition) and for other solid cancers as a group. A significant dose response, with no indication of plutonium exposure effects, was found for leukemia. Excess risks for leukemia exhibited a significant dependence on the time since the dose was received. For doses received within 3 to 5 years of death the excess relative risk per gray was estimated to be about 7 (P < 0.001), but this risk was only 0.45 (P = 0.02) for doses received 5 to 45 years prior to death. External gamma-ray exposures significantly increased risks of both solid cancers and leukemia in this large cohort of men and women with occupational radiation exposures. Risks at doses of less than 1 Gy may be slightly lower than those seen for doses arising from acute exposures in the atomic bomb survivors. As dose estimates for the Mayak workers are improved, it should be possible to obtain more precise estimates of solid cancer and leukemia risks from protracted external radiation exposure in this cohort.

Adult↗
PubMed2002

Alcohol, tobacco and breast cancer--collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease.

Alcohol and tobacco consumption are closely correlated and published results on their association with breast cancer have not always allowed adequately for confounding between these exposures. Over 80% of the relevant information worldwide on alcohol and tobacco consumption and breast cancer were collated, checked and analysed centrally. Analyses included 58,515 women with invasive breast cancer and 95,067 controls from 53 studies. Relative risks of breast cancer were estimated, after stratifying by study, age, parity and, where appropriate, women's age when their first child was born and consumption of alcohol and tobacco. The average consumption of alcohol reported by controls from developed countries was 6.0 g per day, i.e. about half a unit/drink of alcohol per day, and was greater in ever-smokers than never-smokers, (8.4 g per day and 5.0 g per day, respectively). Compared with women who reported drinking no alcohol, the relative risk of breast cancer was 1.32 (1.19-1.45, P<0.00001) for an intake of 35-44 g per day alcohol, and 1.46 (1.33-1.61, P<0.00001) for >/=45 g per day alcohol. The relative risk of breast cancer increased by 7.1% (95% CI 5.5-8.7%; P<0.00001) for each additional 10 g per day intake of alcohol, i.e. for each extra unit or drink of alcohol consumed on a daily basis. This increase was the same in ever-smokers and never-smokers (7.1% per 10 g per day, P<0.00001, in each group). By contrast, the relationship between smoking and breast cancer was substantially confounded by the effect of alcohol. When analyses were restricted to 22 255 women with breast cancer and 40 832 controls who reported drinking no alcohol, smoking was not associated with breast cancer (compared to never-smokers, relative risk for ever-smokers=1.03, 95% CI 0.98-1.07, and for current smokers=0.99, 0.92-1.05). The results for alcohol and for tobacco did not vary substantially across studies, study designs, or according to 15 personal characteristics of the women; nor were the findings materially confounded by any of these factors. If the observed relationship for alcohol is causal, these results suggest that about 4% of the breast cancers in developed countries are attributable to alcohol. In developing countries, where alcohol consumption among controls averaged only 0.4 g per day, alcohol would have a negligible effect on the incidence of breast cancer. In conclusion, smoking has little or no independent effect on the risk of developing breast cancer; the effect of alcohol on breast cancer needs to be interpreted in the context of its beneficial effects, in moderation, on cardiovascular disease and its harmful effects on cirrhosis and cancers of the mouth, larynx, oesophagus and liver.

Adult↗
PubMed2002

Acromegaly and cancer risk: a cohort study in Sweden and Denmark.

OBJECTIVE: Several studies have suggested that patients with acromegaly have an increased risk of benign and malignant neoplasms, especially of the colon. To further investigate this relationship we evaluated cancer risk in population-based cohorts of acromegaly patients in Sweden and Denmark. METHODS: Nationwide registry-based cohorts of patients hospitalized for acromegaly (Denmark 1977-1993; Sweden 1965-1993) were linked to tumor registry data for up to 15-28 years of follow-up, respectively. Standardized incidence ratios (SIR) and 95% confidence intervals (CI) were calculated to estimate cancer risk among 1634 patients with acromegaly. RESULTS: The patterns of cancer risk in Sweden and Denmark were similar. After excluding the first year of follow-up, 177 patients with acromegaly had a diagnosis of cancer compared with an expected number of 116.5 (SIR = 1.5. 95% CI = 1.3-1.8). Increased risks were found for digestive system cancers (SIR = 2.1, 95% CI = 1.62.7), notably of the small intestine (SIR = 6.0, 95% CI = 1.2-17.4), colon (SIR = 2.6, 95% CI = 1.6-3.8), and rectum (SIR = 2.5, 95% CI= 1.3-4.2). Risks were also elevated for cancers of the brain (SIR = 2.7, 95% CI= 1.2-5.0). thyroid (SIR = 3.7, 95% CI = 1.8-10.9), kidney (SIR = 3.2, 95% CI = 1.6-5.5), and bone (SIR= 13.8, 95% CI= 1.7-50.0). CONCLUSIONS: The increased risk for several cancer sites among acromegaly patients may be due to the elevated proliferative and anti-apoptotic activity associated with increased circulating levels of insulin-like growth factor-1 (IGF-1). Pituitary irradiation given to some patients may have contributed to the excess risks of brain tumors and thyroid cancer. Our findings indicate the need for close medical surveillance of patients with acromegaly, and further studies of the IGF-I system in the etiology of various cancers.

Acromegaly↗
PubMed2002

Is the sampling site along the umbilical artery significant?

The purpose of umbilical blood sampling is to obtain accurate reflection of fetal acid-base status at birth. The site along the umbilical artery from which blood should be sampled postpartum was not specified. We evaluated if blood gases and pH values from three sampling sites along the umbilical artery are different. After defining the range of intraobserver (method) variability, blood pO(2), pCO(2), and pH were directly determined. The data showed consistent and significant increases in arterial pH and pCO(2) values and decreases in pO(2) values from near the fetal cord insertion to the placenta. The largest difference was noted between the fetal site and the placental plate and the smallest between the site near the placental cord insertion and the placental plate. We conclude that the site of cord blood sampling should be standardized and the umbilical artery should be sampled at a site nearest to the neonate.

Blood Gas Analysis↗