Cancer incidence among liquidators of the Chernobyl accident: solid tumors, 1986-1995

Trends in Solid Tumor Incidence in Ukraine 30 Years After Chernobyl

PURPOSE

There is limited knowledge of the long-term health effects of the Chernobyl nuclear power plant accident that occurred more than 30 years ago in Ukraine. This study describes trends in the incidence of solid organ malignancy in Ukraine and the five regions most affected by the radioactive fallout.

METHODS

The National Cancer Registry of Ukraine was queried for age-standardized incidence rates (ASIRs) of solid organ malignancy in Ukraine and the regions of Kyiv, Chernihiv, Zhytomyr, Rivne, and Volyn covering the period of 1999 to 2016. Joinpoint analysis was used to calculate the average annual percentage of change.

RESULTS

The highest burdens of cancer incidence in Ukraine were seen in the lung, stomach, breast, and prostate. We observed significant increases in the ASIRs of colon (average annual percentage of change, 1.5 [95% CI, 1.3 to 1.7]), rectal (0.9 [95% CI, 0.6 to 1.2]), kidney (2.3 [95% CI, 1.8 to 2.9]), thyroid (4.2 [95% CI, 3.1 to 5.3]), breast (1 [95% CI, 0.6 to 1.4]), cervical (0.7 [95% CI, 0.3 to 1.2]), and prostate (3.9 [95% CI, 3.6 to 4.2]) cancers, with decreases in stomach (−2.4 [95% CI, −2.5 to −2.3]) and lung (−1.8 [95% CI, −2.1 to −1.5]) cancers. ASIRs in the affected regions were similar to nationwide rates, with the exception of those for Kyiv.

CONCLUSION

The incidence rates of many solid organ malignancies in Ukraine are rising. However, the rates of solid organ malignancy in the five regions most affected by fallout did not substantially differ from national patterns, with the exception of those for Kyiv. Ongoing monitoring of cancer incidence in Ukraine is necessary to understand how best to decrease disease burden nationwide and to elucidate the causes of regional variations in ASIRs, such as access to diagnostics and environmental exposures.

Latent period in induction of radiogenic solid tumors in the cohort of emergency workers

The paper presents estimates for the latent period of the induction of radiogenic solid cancers among Chernobyl emergency workers (males) living in six central regions of Russia. The analysis is based on medical and dosimetry data gathered by the National Radiation and Epidemiological Registry over the time period from 1986 to 2005. The cohort includes 59,770 persons who stayed in the exposure zone (30-km zone around the Chernobyl nuclear power plant) in 1986-1987. There were 2,718 cases of solid tumors identified during the follow-up time in this cohort. The mean radiation dose in the cohort is 0.13 Gy. The radiation risk and latent period were estimated using the method of maximum likelihood. The excess relative risk per unit dose was found to be 0.96 (95% confidence interval (CI): 0.3-1.7) and the minimum latent period for induction of solid tumors is 4.0 years (95% CI: 3.3-4.9).

Estimates of relative risks for cancers in a population after prolonged low-dose-rate radiation exposure: a follow-up assessment from 1983 to 2005

Radiation effects on cancer risks in a cohort of Taiwanese residents who received protracted low-dose-rate gamma-radiation exposures from (60)Co-contaminated reinforcing steel used to build their apartments were studied, and risks were compared to those in other radiation-exposed cohorts. Analyses were based on a more extended follow-up of the cohort population in which 117 cancer cases diagnosed between 1983 and 2005 among 6,242 people with an average excess cumulative exposure estimate of about 48 mGy. Cases were identified from Taiwan's National Cancer Registry. Radiation effects on cancer risk were estimated using proportional hazards models and were summarized in terms of the hazard ratio associated with a 100-mGy increase in dose (HR(100mGy)). A significant radiation risk was observed for leukemia excluding chronic lymphocytic leukemia (HR(100mGy) 1.19, 90% CI 1.01-1.31). Breast cancer exhibited a marginally significant dose response (HR(100mGy) 1.12, 90% CI 0.99-1.21). The results further strengthen the association between protracted low-dose radiation and cancer risks, especially for breast cancers and leukemia, in this unique cohort population.

Sclerosing epithelioid fibrosarcoma of the cecum: a radiation-associated tumor in a previously unreported site

Data from the nuclear reactor explosion in Chernobyl and the atomic bomb detonations in Hiroshima and Nagasaki demonstrated an association between ionizing radiation and tumoriogenesis. There is a significant association between external beam radiation and radiation-induced sarcoma. Sclerosing epithelioid fibrosarcoma is a rare form of malignant fibrosarcoma that is low grade and indolent with distinct immunohistopathologic characteristics that usually occurs in the soft tissues of the extremities. A 62-year-old man from Kiev who aided in the cleanup at Chernobyl presented with crampy abdominal pain, nausea, and vomiting. His workup revealed a cecal mass, and the final pathology from his laparotomy confirmed sclerosing epithelioid fibrosarcoma with metastasis to the liver. In addition to a review of the literature, we report the first case of sclerosing epithelioid fibrosarcoma arising from the large bowel. Exposure to ionizing radiation from Chernobyl could have played a role in the development of his tumor.

Radiation and epidemiological analysis for solid cancer incidence among nuclear workers who participated in recovery operations following the accident at the Chernobyl NPP

This paper discusses the results of the analysis of the relationship between dose and solid cancer incidence among nuclear workers (males) who worked as liquidators after the Chernobyl accident. Information on this cohort of individuals is available at the regional center of Russian National Medical and Dosimetric Registry operating at the RF State Research Centre-Institute of Biophysics. Medical and dosimetric information on 8,654 persons 18-60 years of age with documented external radiation doses is used for the analysis. These data were gathered in the period from 1996 to 2001 and cover a total of 45,166.5 follow-up person-years. In the cohort under study, 179 solid cancers occurred during this period. The average age of liquidators at the time of exposure was 35.8 years, and the average dose as a result of the Chernobyl exposure was about 0.05 Sv. For an analysis of the dose-effect relationship (induction of radiation-induced malignant neoplasms) the statistical software EPICURE was used. The results of the analysis show that the cancer incidence in this cohort does not exceed cancer incidence in relevant age groups of the Russian population. The mean value of SIR for all cancer diseases was 0.88 (0.76, 1.02, 95% CI) for the whole period of follow-up. Risks for the induction of radiation-related cancer diseases were not statistically meaningful. Excess relative risk per 1 Sv was 0.95 (-1.52, 4.49, 95% CI).

Cancer risk around the nuclear power plants of Trillo and Zorita (Spain)

AIM

To investigate the association between cancer risk and proximity of place of residence to the Guadalajara nuclear power plants: Trillo and Zorita.

METHODS

Case-control study. Cases were patients admitted with cancer and controls were non-tumorous patients, both admitted to Guadalajara Hospital (period 1988-99). Exposure factor: place of residence (areas within 10, 20, and 30 km of each plant). Odds ratios (ORs) of those areas closest to the plants were calculated with respect to those furthest away; a linear trend analysis was also performed.

RESULTS

In the extreme areas in the vicinity of Trillo, an OR of 1.71 was obtained (95% CI 1.15 to 2.53), increasing in magnitude in the subgroup of more radioinducible tumours and in the period considered as post-latency (1997-99). Risk increased linearly with proximity to the two plants, significantly in Trillo (p < 0.01) but not in Zorita (p = 0.19).

CONCLUSIONS

There is an association between proximity of residence to Trillo and cancer risk, although the limitations of the study should be kept in mind when interpreting the possible causal relation.

Cancers among Residents Downwind of the Hanford, Washington, Plutonium Production Site

A community-based health survey for the time period between 1944 and 1995 was collected from 801 individuals who had lived downwind of the U.S. plutonium production facility located in Hanford, Washington. The results of the survey revealed high incidences of all cancers, including thyroid cancer. There were greater than expected numbers of central nervous system tumors and cancers that invaded the female reproductive system (e.g., cancers of the uterus, ovary, cervix, and breast). The authors argue that the greater-than-expected numbers found cannot be accounted for by selection bias alone. Comparisons of crude incidence rates, as well as of occurrence ratios between pairs of cancer types among Downwinders and reasonably similar populations, suggested that the excess neoplasms may be associated with radioactive contamination of food, water, soil, and/or air. In addition, a synergistic effect may exist with agricultural toxins. Previously neglected biophysical and physiological properties of internally lodged, long-lived 129I may be a significant etiological factor in the development of thyroid diseases, including cancer, and other malignancies in exposed populations.

Chernobyl-related ionising radiation exposure and cancer risk: an epidemiological review

The Chernobyl nuclear accident on 26th April, 1986, led to a massive release of radionuclides into the environment. Although vast areas of Europe were affected by Chernobyl-related ionising radiation, the accident had the greatest impact in Belarus, Ukraine, and the Russian Federation. Epidemiological studies that have investigated the link between the Chernobyl accident and cancer have largely focused on malignant diseases in children, specifically thyroid cancer and leukaemia. There is good evidence to suggest that rates of thyroid cancer in children from the countries that were formally part of the Soviet Union have risen as a consequence of the Chernobyl accident. The findings for childhood leukaemia are less conclusive. Overall rates for this disease do not seem to have been affected by the Chernobyl-related ionising radiation, but there may be a larger risk of infant leukaemia in contaminated areas of Europe. Among adult populations, there is no strong evidence to suggest that risk of thyroid cancer, leukaemia, or other malignant disease has increased as a result of the Chernobyl accident.

Mortality among the Chernobyl emergency workers: estimation of radiation risks (preliminary analysis)

This paper presents results of the analysis of mortality among Chernobyl accident emergency workers who are resident in Russia. The analysis is based on information for the cohort of emergency workers (males) from six regions of Russia including 65,905 persons with documented external doses in the range 0.005-03 Sv. These data were gathered during the period 1991 to 1998 and cover a total of 426,304 follow-up person-y. In this period, 4,995 deaths occurred in the cohort under study. The mortality analysis was performed for four groups of causes of death (ICD-9 codes): (1) malignant neoplasms (140-239); (2) cardiovascular diseases (390-459); (3) injuries, poisoning and violent deaths, (800-999); and (4) the remainder (other than the above). The standardized mortality rate for groups 1, 3, and 4 is less than unity and varies from 0.6 to 0.9. For group 2 (death from cardiovascular diseases) the standardized mortality rate conforms with the control within 95% confidence intervals. The control was the mortality rate (males) for the corresponding ages in Russia in general and the internal control, the spontaneous mortality among emergency workers, derived from the equation of the observed and expected number of cases in the followed up cohort. Dose response of mortality was studied. Statistically significant radiation risks were obtained for mortality from malignant neoplasms (515 cases) and cardiovascular diseases (1,728 cases). The values of the excess relative risk per unit dose (ERR Sv(-1)) for malignant neoplasms and cardiovascular diseases are estimated as 2.11 (1.31, 2.92 95% CI) and 0.54 (0.18,0.91 95% CI) (for external control), 2.04 (0.45, 4.31 95% CI) and 0.79 (0.07, 1.64 95% CI) (for internal control), respectively. The risk of death from all noncancer causes is close to zero and not statistically significant.

Cancer Incidence among Nuclear Workers in Russia Based on Data from the Institute of Physics and Power Engineering: A Preliminary Analysis

One group that has the potential to be exposed to radiation is workers in the nuclear industry. Results of a systematic medical follow-up and dosimetric monitoring of these workers can form the basis for a study of the relationship between cancer incidence and radiation dose. As part of such efforts in Russia, a major institution of the nuclear industry with an established medical care unit, archiving capabilities, and dosimetry department was selected: the Institute of Physics and Power Engineering (IPPE) in Obninsk. In the study, a comparative analysis of cancer incidence rates for the IPPE workers and for the general population of Russia in 1991-1997 was carried out. The subjects were the IPPE workers hired before 1981. This restriction was imposed to reduce the uncertainty associated with the possible latent period in the development of solid cancers. Thus the possibility of including persons who already had the disease at the time when they were hired was minimized. The analysis is based on information about 158 cancer cases, including 24 cancers in persons under individual dosimetric monitoring. A statistically significant excess in cancer incidence was found among the IPPE workers compared with a comparison population (the general population of Russia) for some types of cancers. The SIR values for all cancers (ICD-9: 140-208) is 0.93 (95% CI 0.76, 1.12) for males and 1.42 (95% CI 1.06, 1.87) for females. A statistically significant excess for all cancers was also observed for residents of Obninsk compared to the control comparison population. The corresponding SIR value was 1.20 (95% CI 1.12, 1.28) for males and 1.58 (95% CI 1.49, 1.69) for females. An important reason for the observed excess in cancer incidence compared to the control population may be the higher level of health care in the so-called nuclear cities of Russia which may have resulted in increased diagnosis and registration of cancers. A statistically significant dependence of the cancer incidence on the dose of ionizing radiation was not established. The excess relative risk per gray for all types of cancer was 0.91 (95% CI -2.75, 4.61) for males and 0.40 (95% CI -6.94, 7.83) for females. These estimates should be considered to be preliminary, as the number of cases considered in the analysis of the dose response is small (17 males and 7 females).

Radiation-epidemiological analysis of incidence of non-cancer diseases among the Chernobyl liquidators

The work is concerned with assessment of radiation risks for non-cancer disease among the Chernobyl liquidators from 1986 to 1996. As of 1 January 1999, the Russian National Medical and Dosimetric Registry contains medical and dosimetric data for 174,000 liquidators. The cohort of 68,309 liquidators for whom best verified medical data are available is discussed. The dose dependency of incidence of non-cancer diseases was estimated by the cohort method and using the software package Epicure. For some classes of non-cancer diseases among liquidators, statistically significant estimates of radiation risk were derived for the first time. The highest excess relative risk per 1 Gy was found for cerebrovascular diseases; ERR Gy(-1)=1.17 at the 95% confidence interval (0.45; 1.88).