Second Primary Cancer Among Patients With Papillary Thyroid Carcinoma Following the Chernobyl Disaster.

Importance: To our knowledge, there are no complete population-based studies of the risks of developing second malignant tumors after papillary thyroid carcinoma (PTC) in patients following the Chernobyl nuclear accident. Objective: To study the risk of second primary cancers in patients with PTC after the Chernobyl disaster. Design, Setting, and Participants: This was a retrospective cohort study conducted in the Republic of Belarus over a 31-year time frame evaluating patients with primary PTC and second malignant tumors. Personal data from the Belarussian Cancer Registry were used in the investigation, and only second primary cancers were included in the analysis. Patients were observed from January 1, 1990, to December 31, 2021, for the establishment of second primary malignant tumors. Main Outcomes and Measures: For analysis, synchronous and metachronous tumors were grouped into 1 group (second primary cancer group). If the patient had more than 2 cancers, they were observed until development of a second tumor and, subsequently, the development of a third tumor. The starting point for calculating the number of person-years was the date of thyroid cancer diagnosis. The end point for calculating the number of person-years was the date of diagnosis of the second primary malignant tumor, the date of death, the date of the last visit of the patient, or December 31, 2021 (the end the of study period). The incidence of a second primary malignant tumor with PTC was calculated for the study groups using standardized incidence ratios. Results: Of the 30 568 patients with a primary PTC included in this study, 2820 (9.2%) developed a second malignant tumor (2204 women and 616 men); the mean (SD) age of all patients at time of the primary cancer was 53.9 (12.6) years and at time of the secondary cancer was 61.5 (11.8) years. Overall, the standardized incidence ratio was statistically significant for all types of cancer (1.25; 95% CI, 1.21-1.30), including solid malignant tumors (1.20; 95% CI, 1.15-1.25) and all leukemias (1.61; 95% CI, 2.17-2.13). Cancers of the digestive system (466 cases [21.1%]), genital organs (376 cases [17.1%]), and breasts (603 cases [27.4%]) were the most prevalent second primary tumors in women following PTC. Second primary tumors of the gastrointestinal tract (146 cases [27.7%]), genitourinary system (139 cases [22.6%]), and urinary tract (139 cases [22.6%]) were the most prevalent in men. Urinary tract cancers (307 cases [10.9%]) and gastrointestinal tumors (612 cases [21.4%]) were the most prevalent second primary tumors overall. Conclusions and Relevance: This cohort study reports the increased incidence of solid secondary tumors in men and women over a 31-year time frame after the Chernobyl disaster. Moreover, there was a statistically significant increased risk of second tumors of the breast, colon, rectum, mesothelium, eye, adnexa, meninges, and adrenal glands as well as Kaposi sarcoma. These data might have an effect on the follow-up of this cohort of patients to detect secondary malignant tumors at an early stage.

Recall of residential history and dietary habits during pregnancy and lactation in the distant past: reliability of questionnaire-based radiation doses for persons exposed in utero and early life.

This study evaluates the reliability of information obtained by standardized questionnaires used in by personal interviews for estimation of radiation thyroid doses of 1065 individuals in the Belarusian cohort of individuals who were exposed in utero and early life following the Chernobyl accident in April 1986. Data from two interviews conducted in 2012-2017 and in 2018-2022 with mothers, who were pregnant or gave birth shortly after the Chernobyl accident, were analysed. The most reliable answers dealt with various attributes related to residential history. In contrast, the reliability of answers regarding consumption rates of milk from privately owned cows or trade network was moderate, while the agreement in responses for consumption of milk products and leafy vegetables was fair. Information from the two interviews was used to calculate thyroid doses received by the cohort members. Specifically, 'model-based' thyroid doses due to 131I were estimated using input data on individual residential history and food consumption reported during the personal interviews and ecological data (131I ground deposition in the corresponding settlements). In addition, for a subset of cohort subjects (n = 205) whose mothers were measured for 131I thyroid activity, 'measurement-based' thyroid doses were calculated by adjusting the model-based dose using a scaling factor that is defined as the ratio of measured 131I thyroid activity to model-based 131I thyroid activity calculated for the date of measurement. A moderate agreement was observed for total (prenatal and postnatal) model-based thyroid doses due to 131I intake, the arithmetic mean ± standard deviation for the Jaccard similarity coefficient ([Formula: see text]) was 0.45 ± 0.34 (median = 0.39), while measurement-based doses showed a much better agreement with a [Formula: see text] of 0.78 ± 0.29 (median = 0.93). For model-based thyroid doses from external irradiation and from ingestion of 134Cs and 137Cs, [Formula: see text] was 0.82 ± 0.23 (median = 0.90) and 0.84 ± 0.24 (median = 0.96), respectively. Measurement-based doses due to ingestion of radiocaesium isotopes resulted in an almost perfect agreement, [Formula: see text] was 0.91 ± 0.19 (median = 1.0). The present findings suggest that long-term memory recall can be reliable, if a person is asked about unique or important life events, such as pregnancy and childbirth occurring around the time of a nuclear reactor accident. However, the substantial difference (more than 10 times) observed for model-bases doses calculated using the two questionnaires represents an important source of human factor uncertainties that needs to be considered in any dose response analyses. Other lessons learned from this study are that (i) individual measurements of radionuclides in the human body are the most valuable source of information for estimating radiation doses, and (ii) whenever a radiation accident occurs, a sample of affected people should be asked to keep a diary, if at all possible.

Association between exposure to radioactive iodine after the Chernobyl accident and thyroid volume in Belarus 10-15 years later.

BACKGROUND: While there is a robust literature on environmental exposure to iodine-131 (131I) in childhood and adolescence and the risk of thyroid cancer and benign nodules, little is known about its effects on thyroid volume. METHODS: To assess the effect of 131I dose to the thyroid on the volume of the thyroid gland, we examined the data from the baseline screening of the Belarusian-American Cohort Study of residents of Belarus who were exposed to the Chernobyl fallout at ages ≤18 years. Thyroid dose estimates were based on individual thyroid activity measurements made shortly after the accident and dosimetric data from questionnaires obtained 10-15 years later at baseline screening. During baseline screening, thyroid gland volume was assessed from thyroid ultrasound measurements. The association between radiation dose and thyroid volume was modeled using linear regression where radiation dose was expressed with power terms to address non-linearity. The model was adjusted for attained age, sex, and place of residence, and their modifying effects were examined. RESULTS: The analysis was based on 10,703 subjects. We found a statistically significant positive association between radiation dose and thyroid volume (P < 0.001). Heterogeneity of association was observed by attained age (P < 0.001) with statistically significant association remaining only in the subgroup of ≥18 years at screening (P < 0.001). For this group, increase in dose from 0.0005 to 0.15 Gy was associated with a 1.27 ml (95% CI: 0.46, 2.07) increase in thyroid volume. The estimated effect did not change with increasing doses above 0.15 Gy. CONCLUSIONS: This is the first study to examine the association between 131I dose to the thyroid gland and thyroid volume in a population of individuals exposed during childhood and systematically screened 10-15 years later. It provides evidence for a moderate statistically significant increase in thyroid volume among those who were ≥ 18 years at screening. Given that this effect was observed at very low doses and was restricted to a narrow dose range, further studies are necessary to better understand the effect.

Comparative pathological characteristics of papillary thyroid carcinoma with second primary non-thyroid malignancies in the region affected by the Chernobyl accident.

The aim was to study the pathological features of papillary thyroid carcinoma diagnosed with or before second primary malignancy in patients exposed to post-Chernobyl exposure. The patients selected (n = 6559) were those exposed to radiation at the age of ≤ 18 years old and developed papillary thyroid carcinoma during the years 1990-2020. Of these, 2.1% (n = 140) had second primary malignancies. To compare the histopathological characteristics of papillary thyroid carcinoma in the group under analysis, 91% (n = 128) with sufficient data were included in further analysis. The control group was formed by matching patients with age at exposure to radiation, age at surgery, gender, and place of residence. Median age at exposure was 14 years old for both groups. Besides, no difference in tumour extension and histological features of papillary thyroid carcinoma was noted between patients with synchronous or metachronous primary malignant tumours. Nevertheless, the time lag to the diagnosis of papillary thyroid carcinoma was shortened in the group with metachronous when compared to patients with synchronous second primaries (p < 0.001). Independent differences between patients with second primaries and their matched peers included tumour size {OR (95%CI) = 0.89 (0.45; 1.04)}, multiple tumours {OR (95% CI) = 1.46 (0.86; 2.42)}, lymphatic vessel invasion (OR (95%CI) 0.92 (0.61; 1.53)), blood vessel invasion (OR (95%CI) 0.41 (0.10; 1.23) and presence of numerous psammomas (OR (95%CI) 0.73 (0.39; 1.31)). The possible influence of radiative iodine treatment for development of second primaries was analysed for the group of patients with metachronous malignancies using the same approach (84 patients were compared to 252 matched patients). Independent differences also included tumour size {OR (95% CI) 0.77 (0.45; 1.30)}, lymphatic vessel invasion {OR (95%CI) 0.75(0.43; 1.28)}, blood vessel invasion {OR (95%CI) 0.17 (0.01; 0.87)}. Besides, multiple tumours were revealed more frequently in patients with metachronous primaries (OR (95%CI) 1.92 (1.0; 3.62)). To conclude, patients exposed to Chernobyl irradiation with the development of papillary thyroid carcinoma and second primary malignancy have less biological aggressive pathological characteristics of their thyroid cancers. Accordingly, these patients were less frequently treated with post-surgical radioactive iodine. Thus, 131I-irradiation may have negligible impact on the development of second primaries.

Thyroid dose estimates for the genome-wide association study of thyroid cancer in persons exposed in Belarus to 131I after the Chernobyl accident.

The Chernobyl accident on 26 April 1986 led to a sharp increase in thyroid cancer (TC) incidence in the individuals exposed to radiation in childhood. The major risk factor for TC was exposure to Iodine-131 (131I). Here, we estimated the thyroid doses due to 131I intake for 2041 participants of the genome-wide association study of TC in Belarusian people exposed to radioactive fallout from the Chernobyl accident. The following parameter-values specially developed in this study were used to estimate individual thyroid doses: (i) scaling factors for adjustment of the model-based doses, (ii) age and gender diet to characterize 131I intake, and (iii) area-, age- and gender-specific S-values for the thyroid gland per 131I decay in the thyroid. The most reliable doses were calculated for 103 people with measured 131I thyroid activity (the arithmetic mean of 1.2 Gy, median 0.52 Gy), and 275 individuals with detailed residential history and dietary data (the arithmetic mean of 0.41 Gy, median 0.24 Gy). The arithmetic mean of thyroid doses among all study participants was 0.23 Gy (median 0.082 Gy); the highest individual dose was 9.0 Gy. Special attention was paid to the reliability and validity of the obtained estimates, in particular for the individuals without 131I thyroid activity measurements and individual data on residential history and diet, by comparing those with the doses from other post-Chernobyl epidemiological studies. Overall, the doses estimated in the current study were in reasonable agreement with previously reported thyroid doses. These doses will be used in the genome-wide association study of TC in people exposed in Belarus to 131I after the Chernobyl accident.

Breast cancer incidence in the regions of Belarus and Ukraine most contaminated by the Chernobyl accident: 1978 to 2016.

Even 30 years after the accident, an association between breast cancer incidence and ionizing radiation exposure from Chernobyl fallout remains uncertain. We studied breast cancer incidence in the most contaminated regions of Belarus (Gomel and Mogilev) and Ukraine (Kyiv, Zhytomyr and Chernihiv) before (1978-1986) and after (1987-2016) the accident. Breast cancer cases and female population size data were received from the national cancer registries and the state departments of statistics. The study included 85 132 breast cancers with 150 million person-years at risk. We estimated annual rayon (district)-average absorbed doses to the breast from external and internal irradiation of the adult female population over the period of 1986-2016. We studied an association between rayon-average cumulative absorbed breast dose with 5-year lag, that is, excluding the exposure in 5 years prior to breast cancer diagnosis, and breast cancer incidence using negative binomial regression models. Mean (median) cumulative breast dose in 2016 was 12.3 (5.0) milligray (mGy) in Belarus and 5.7 (2.3) mGy in Ukraine, with the maximum dose of 55 mGy and 54 mGy, respectively. Breast cancer incidence rates statistically significantly increased with calendar year and attained age, and were higher in urban than in rural residents. Adjusting for time, age and urbanicity effects, we found no evidence of increasing incidence with rayon-average 5-year lagged cumulative breast dose. Owing to ecological study design limitations, a case-control study covering this area with individually reconstructed absorbed breast doses is needed testing for association between low-dose protracted radiation exposure and breast cancer risk after Chernobyl.

Second primary malignancies in patients with papillary thyroid carcinoma after effect of post-chernobyl irradiation: A risk analysis of more than two decades of observations.

BACKGROUND: Second primary malignancy in patients with papillary thyroid carcinoma after Chernobyl accident is an emerging problem. The aims of the study are to investigate the rates and distribution of second primary malignant tumours in Belarus survivors of post-Chernobyl papillary thyroid carcinoma and the cumulative rate of developing a second primary malignancy in a group of patients with metachronous second primaries. METHODS: Patients aged 18 or younger at the time of Chernobyl accident who were diagnosed with papillary thyroid carcinoma after 1986 were identified from the Belarus Cancer Registry. The clinical and demographic of these patients were analysed to correlate with the factors for the development of secondary primary cancer. RESULTS: Secondary primary cancer was detected in 1.8 % (119 of 6559) of the patients with papillary thyroid carcinoma. The cumulative incidence tended to rise with increasing age of the cohort and varied depending on the sex of patients. In female patients, breast carcinoma and genital tract carcinomas prevailed, in men patients - lymphoma/ leukaemia and the alimentary tract malignancies predominated. A significant excess risk was revealed for breast carcinoma in females, colon carcinoma in males, and the urinary system carcinomas in males (absolute excess risk [AER] = 3.23, 3.01 and 2.17 correspondingly). Overall, our results pointed to the increased risk of new solid primaries in females, males and both genders (AER = 3.31, 7.19, 4.28 correspondingly) as well as increase risk of lymphoid/hematopoietic malignancies in females and both genders (AER = 1.24) and leukaemia in male patients (AER = 1.45). CONCLUSION: Patients with papillary thyroid carcinoma after Chernobyl accident are at risk of secondary primary malignancy. Awareness and screening of secondary cancer is needed for patients with papillary thyroid carcinoma after Chernobyl accident.

Uncertainties in Radiation Doses for a Case-control Study of Thyroid Cancer among Persons Exposed in Childhood to 131 I from Chernobyl Fallout.

Uncertainties in thyroid doses due to I intake were evaluated for 2,239 subjects in a case-control study of thyroid cancer following exposure to Chernobyl fallout during childhood and adolescence carried out in contaminated regions of Belarus and Russia. Using new methodological developments that became available recently, a Monte Carlo simulation procedure was applied to calculate 1,000 alternative vectors of thyroid doses due to I intake for the study population of 2,239 subjects accounting for sources of shared and unshared errors. An overall arithmetic mean of the stochastic thyroid doses in the study was estimated to be 0.43 Gy and median dose of 0.16 Gy. The arithmetic mean and median of deterministic doses estimated previously for 1,615 of 2,239 study subjects were 0.48 Gy and 0.20 Gy, respectively. The geometric standard deviation of individual stochastic doses varied from 1.59 to 3.61 with an arithmetic mean of 1.94 and a geometric mean of 1.89 over all subjects of the study. These multiple sets of thyroid doses were used to update radiation-related thyroid cancer risks in the study population exposed to I after the Chernobyl accident.

Belarusian in utero cohort: A new opportunity to evaluate the health effects of prenatal and early-life exposure to ionising radiation.

In April 1986, the Chernobyl nuclear accident resulted in wide-scale contamination of Belarus with significantly elevated levels of radioiodine isotopes, mainly iodine-131 (131I), and long-lived radiocaesium isotopes, mainly caesium-137 (137Cs). Various groups of the population were affected by exposure to ionising radiation, including pregnant women and their foetuses. This paper describes the methods and results related to the establishment of a cohort of 2965 Belarusian people exposed in utero due to Chernobyl fallout. The cohort consists of individuals whose mothers resided in the most radioactively contaminated areas in Belarus at the time of the accident. Prenatal and postnatal doses to the thyroid due to intake of 131I, external irradiation and ingestion of radiocaesium isotopes were estimated for all cohort members. Ongoing research on this unique cohort will provide important information on adverse health effects following prenatal and postnatal exposure to radioiodine and radiocaesium isotopes, for which available epidemiological data are scant.

Thyroid Cancer after Exposure to Radioiodine in Childhood and Adolescence: 131I-Related Risk and the Role of Selected Host and Environmental Factors.

In this study, we expanded on a previously published population-based case-control study on subjects exposed to iodine-131 (131I) from Chernobyl fallout at age ≤18 years using improved individual 131I absorbed thyroid doses. We further studied the impact of iodine deficiency and other selected host risk factors on 131I-related thyroid cancer risk after childhood exposure. We included 298 thyroid cancer cases and 1934 matched controls from the most contaminated regions of Belarus and the Russian Federation. We performed statistical analysis using conditional logistic regression models. We found a statistically significant linear quadratic dose-effect association between thyroid cancer and 131I thyroid dose in the range up to 5 grays (Gy). Self-reported personal history of benign nodules, any thyroid disease except thyroid cancer, family history of thyroid cancer, increased body mass index, and deficient stable iodine status at the time of the accident were statistically significant risk factors (p < 0.05 for each factor) for thyroid cancer after adjustment for thyroid 131I dose effect. Subjects who received stable iodine supplementation in the years after the accident had a significantly lower 131I-related risk of thyroid cancer. Our findings are important for thyroid cancer prevention, and for further improvement of medical surveillance in the affected populations.

Risk of Thyroid Nodules in Residents of Belarus Exposed to Chernobyl Fallout as Children and Adolescents.

Context: Although radiation exposure is an important predictor of thyroid cancer on diagnosis of a thyroid nodule, the relationship between childhood radiation exposure and thyroid nodules has not been comprehensively evaluated. Objective: To examine the association between internal I-131 thyroid dose and thyroid nodules in young adults exposed during childhood. Design, setting, and participants: In this cross-sectional study, we screened residents of Belarus aged ≤18 years at the time of the Chernobyl nuclear accident for thyroid disease (median age, 21 years) with thyroid palpation, ultrasonography, blood/urine analysis, and medical follow-up when appropriate. Eligible participants (N = 11,421) had intact thyroid glands and doses based on direct individual thyroid activity measurements. Main outcome measures: Excess odds ratios per Gray (EOR/Gy, scaled at age 5 years at exposure) for any thyroid nodule and for nodules grouped by cytology/histology, diameter size, and singularity. Results: Risk of any thyroid nodule increased significantly with I-131 dose and, for a given dose, with younger age at exposure. The EOR/Gy (95% confidence intervals) for neoplastic nodules (3.82; 0.87 to 15.52) was significantly higher than for nonneoplastic nodules (0.32; <0.03 to 0.70) and did not vary by size; whereas the EOR/Gy for nonneoplastic nodules did vary by size (P = 0.02) and was 1.55 (0.36 to 5.46) for nodules ≥10 mm and 0.02 (<-0.02 to 0.70) for nodules <10 mm. EORs/Gy for single and multiple nodules were comparable. Conclusions: Childhood exposure to internal I-131 is associated with increased risk of neoplastic thyroid nodules of any size and nonneoplastic nodules ≥10 mm.

Non-thyroid cancer incidence in Belarusian residents exposed to Chernobyl fallout in childhood and adolescence: Standardized Incidence Ratio analysis, 1997-2011.

BACKGROUND: While an increased risk of thyroid cancer from post-Chernobyl exposure to Iodine-131 (I-131) in children and adolescents has been well-documented, risks of other cancers or leukemia as a result of residence in radioactively contaminated areas remain uncertain. METHODS: We studied non-thyroid cancer incidence in a cohort of about 12,000 individuals from Belarus exposed under age of 18 years to Chernobyl fallout (median age at the time of Chernobyl accident of 7.9 years). During 15 years of follow-up from1997 through 2011, 54 incident cancers excluding thyroid were identified in the study cohort with 142,968 person-years at risk. We performed Standardized Incidence Ratio (SIR) analysis of all solid cancers excluding thyroid (n=42), of leukemia (n=6) and of lymphoma (n=6). RESULTS: We found no significant increase in the incidence of non-thyroid solid cancer (SIR=0.83, 95% Confidence Interval [CI]: 0.61; 1.11), lymphoma (SIR=0.66, 95% CI: 0.26; 1.33) or leukemia (SIR=1.78, 95% CI: 0.71; 3.61) in the study cohort as compared with the sex-, age- and calendar-time-specific national rates. These findings may in part reflect the relatively young age of study subjects (median attained age of 33.4 years), and long latency for some radiation-related solid cancers. CONCLUSIONS: We found no evidence of statistically significant increases in solid cancer, lymphoma and leukemia incidence 25 years after childhood exposure in the study cohort; however, it is important to continue follow-up non-thyroid cancers in individuals exposed to low-level radiation at radiosensitive ages.

Risk of thyroid follicular adenoma among children and adolescents in Belarus exposed to iodine-131 after the Chornobyl accident.

Several studies reported an increased risk of thyroid cancer in children and adolescents exposed to radioactive iodines, chiefly iodine-131 ((131)I), after the 1986 Chornobyl (Ukrainian spelling) nuclear power plant accident. The risk of benign thyroid tumors following such radiation exposure is much less well known. We have previously reported a novel finding of significantly increased risk of thyroid follicular adenoma in a screening study of children and adolescents exposed to the Chornobyl fallout in Ukraine. To verify this finding, we analyzed baseline screening data from a cohort of 11,613 individuals aged ≤18 years at the time of the accident in Belarus (mean age at screening = 21 years). All participants had individual (131)I doses estimated from thyroid radioactivity measurements and were screened according to a standardized protocol. We found a significant linear dose response for 38 pathologically confirmed follicular adenoma cases. The excess odds ratio per gray of 2.22 (95% confidence interval: 0.41, 13.1) was similar in males and females but decreased significantly with increasing age at exposure (P < 0.01), with the highest radiation risks estimated for those exposed at <2 years of age. Follicular adenoma radiation risks were not significantly modified by most indicators of past and current iodine deficiency. The present study confirms the (131)I-associated increases in risk of follicular adenoma in the Ukrainian population and adds new evidence on the risk increasing with decreasing age at exposure.

Retrospective cohort study of cancer mortality at the Minsk Leather Tannery.

The cohort of 768 workers who were actively employed for a minimum of 6 months and died was retrospectively followed from 1 January 1953 to 31 December 2000. There were 328 women and 440 men observed. Proportionate mortality ratios (PMRs) were calculated using the Minsk-city population mortality proportions to generate expected numbers. The significant excess of pancreatic cancer (PMR=366%; 95%CI=134-800) and melanoma and skin cancer (PMR=455%; 95% CI=123-1,164) in women-workers of Dyeing and stuffing workshops was shown. The significantly high mortality from pancreatic cancer among Dyeing and stuffing workshops' female workers hired and discharged between 1958 and 1984 (PMR=1,024%; 95% CI=11-2,109), melanoma and skin cancer (PMR=440%; 95% CI=240-2,327) among Dyeing and stuffing workshops female workers who started before 1970, lip and buccal cavity among men who began working within 1974-1978 (PMR=1,071%; 95% CI=220-3,128), cervix and corpus uteri cancer among workers employed before l960 was found. It should be noted that the significantly high mortality from above noted cancers was indicated for Dyeing and stuffing workshops female workers with seniority more than 10 yr. Thus it was shown for pancreatic cancer (PMR=418%; 95% CI=136-975), for melanoma and skin cancers (PMR=497%; 95% CI=102-1,450), for uterus cancers (PMR=269%; 95% CI=130-496).

Proportionate cancer mortality among workers in the Belarussian tanning industry.

BACKGROUND: The tanning industry involves many occupational exposures. This study evaluates proportionate cancer mortality among workers employed in the Belarussian tanning plant in Minsk. METHODS: A total of 768 workers with seniority of not less than 6 months who were hired after January 1, 1953 and died before December 31, 2000 was investigated. Proportionate mortality ratios (PMRs) were calculated using the population of Minsk to generate expected numbers. RESULTS: Among women employed in the tannery, there was a significant excess of pancreatic cancer, based on eight deaths (expected = 2.56, PMR = 3.13, 95% CI = 1.35-6.17). Six of the eight pancreatic cancer deaths occurred among women occupied in dyeing-stuffing workshops (expected = 1.64, PMR = 3.67, 95% CI = 1.34-7.97), all among workers hired between 1962 and 1984 (expected = 1.06, PMR = 6.54, 95% CI = 2.6-13.4). CONCLUSIONS: Women in this tanning industry cohort experienced excess mortality of cancer of the pancreas, with suggested increases of corpus and cervix uteri, melanoma, and kidney cancers. For men, an insignificant increase in PMR of oral cavity-pharynx and pancreatic cancers was seen. Further prospective follow-up of living members of this cohort, will allow more in-depth analysis of rare cancer sites, latency, and duration of employment, and is warranted.