Biomedical subjects

Lydia B Zablotska

Publications and source records attributed to Lydia B Zablotska.

9 recordsLinked to original sources

PubMed2006

A cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: pathology analysis of thyroid cancer cases in Ukraine detected during the first screening (1998-2000).

BACKGROUND: The Ukrainian American Cohort Study evaluated the risk of thyroid disorders in a group of individuals who were younger than age 18 years at the time of the Chornobyl (Chernobyl) accident. In this article, the authors describe the pathology of thyroid carcinomas detected in the first screening. METHODS: From 1998 to 2000, 13,243 individuals completed the first cycle of screening examinations. Eighty patients underwent surgery between 1998 and 2004. Intraoperative and postoperative pathologic studies were performed at the Institute of Endocrinology and Metabolism, Kyiv. RESULTS: Pathologic analysis revealed 45 thyroid carcinomas, including 43 papillary thyroid carcinomas (PTCs) (95.6%) and 2 follicular thyroid carcinomas (FTCs) (4.4%). TNM classification (5th edition) of the PTCs included 8 T1 tumors (18.6%), 16 T2 tumors (37.2%), and 19 T4 tumors (44.2%). Fifteen PTCs (34.9%) were N1a,N1b, and 3 PTCs (7.0%) were M1. Among the PTCs, 8 exhibited the classical papillary histologic pattern (18.6%), 14 exhibited a follicular histologic pattern (32.6%), 5 exhibited a solid histologic pattern (11.6%), and 16 exhibited a mixed histologic pattern (37.2%). Both FTCs had a microfollicular-solid structure. Eleven of 20 cohort members who underwent surgery before the first screening had PTCs. Regional metastases (63.6%) and distant metastases (18.2%) were more common in this group. CONCLUSIONS: Multifocal growth, lymphatic and blood vessel invasion, extrathyroid spread, and regional and distant metastases were more frequent in less differentiated PTCs (>30% solid structure). Small carcinomas (</=10 mm) comprised 23.3% of PTCs, and most of those (8 of 10 small carcinomas; 80%) were of the papillary-follicular subtype and therefore were more differentiated. The solid subtype of PTC was associated with shorter latency, especially in individuals who were diagnosed before the first screening. The histology of post-Chornobyl cancers is changing with time.

Adenocarcinoma, Follicular↗

PubMed2006

A cohort study of thyroid cancer and other thyroid diseases after the chornobyl accident: thyroid cancer in Ukraine detected during first screening.

BACKGROUND: The Chornobyl accident in 1986 exposed thousands of people to radioactive iodine isotopes, particularly (131)I; this exposure was followed by a large increase in thyroid cancer among those exposed as children and adolescents, particularly in Belarus, the Russian Federation, and Ukraine. Here we report the results of the first cohort study of thyroid cancer among those exposed as children and adolescents following the Chornobyl accident. METHODS: A cohort of 32 385 individuals younger than 18 years of age and resident in the most heavily contaminated areas in Ukraine at the time of the accident was invited to be screened for any thyroid pathology by ultrasound and palpation between 1998 and 2000; 13 127 individuals (44%) were actually screened. Individual estimates of radiation dose to the thyroid were available for all screenees based on radioactivity measurements made shortly after the accident and on interview data. The excess relative risk per gray (Gy) was estimated using individual doses and a linear excess relative risk model. RESULTS: Forty-five pathologically confirmed cases of thyroid cancer were found during the 1998-2000 screening. Thyroid cancer showed a strong, monotonic, and approximately linear relationship with individual thyroid dose estimate (P<.001), yielding an estimated excess relative risk of 5.25 per Gy (95% confidence interval [CI] = 1.70 to 27.5). Greater age at exposure was associated with decreased risk of radiation-related thyroid cancer, although this interaction effect was not statistically significant. CONCLUSION: Exposure to radioactive iodine was strongly associated with increased risk of thyroid cancer among those exposed as children and adolescents. In the absence of Chornobyl radiation, 11.2 thyroid cancer cases would have been expected compared with the 45 observed, i.e., a reduction of 75% (95% CI = 50% to 93%). The study also provides quantitative risk estimates minimally confounded by any screening effects. Caution should be exercised in generalizing these results to any future similar accidents because of the potential differences in the nature of the radioactive iodines involved, the duration and temporal patterns of exposures, and the susceptibility of the exposed population.

Adolescent↗

PubMed2005

Increased risk of squamous cell esophageal cancer after adjuvant radiation therapy for primary breast cancer.

Prior studies have demonstrated that adjuvant radiation therapy following mastectomy for breast cancer increases the risk of second primary esophageal cancer after 10 years, but the risk following breast-conserving surgery (lumpectomy) has yet to be determined. The authors used 1973-2000 data from the population-based Surveillance, Epidemiology, and End Results Program and estimated relative risks of 2.83 (95% confidence interval: 1.35, 5.92) and 2.17 (95% confidence interval: 1.67, 4.02) for squamous cell esophageal cancer at 5-9 and > or =10 years, respectively, following postmastectomy radiation therapy. This increase was mainly due to tumors located in the upper and middle thirds of the esophagus. No significant increase in risk was found for adenocarcinoma following mastectomy or for any type of esophageal cancer following lumpectomy. In summary, postmastectomy radiation therapy moderately increases the risk of squamous cell esophageal cancer starting 5 years after exposure, which persists after 10 years, with no increase in the risk of adenocarcinoma. This finding appears to be a function of the portals used for postmastectomy radiation therapy, which do not expose the lowest third of the esophagus, where adenocarcinomas commonly arise.

Adenocarcinoma↗

PubMed2004

Therapy-induced thoracic malignancies.

As the number of cancer survivors in the United States continues to grow, clinicians must be aware of the possible therapy-related second primary malignancies to which their patients are susceptible. No guidelines have been established for the routine screening of cancer survivors for thoracic malignancies, such as lung cancer, esophageal cancer, and pleural mesothelioma. In general, clinicians should remain cognizant of the fact that previous radiation for a variety of malignancies may have increased their patient's risk for developing a therapy-induced second primary tumor within the thorax. Potential signs and symptoms of thoracic malignancies should be approached with heightened vigilance in any patient who has a history of radiation exposure, regardless of how remote.

Case-Control Studies↗

PubMed2004

A cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: objectives, design and methods.

The thyroid gland in children is one of the organs that is most sensitive to external exposure to X and gamma rays. However, data on the risk of thyroid cancer in children after exposure to radioactive iodines are sparse. The Chornobyl accident in Ukraine in 1986 led to the exposure of large populations to radioactive iodines, particularly (131)I. This paper describes an ongoing cohort study being conducted in Belarus and Ukraine that includes 25,161 subjects under the age of 18 years in 1986 who are being screened for thyroid diseases every 2 years. Individual thyroid doses are being estimated for all study subjects based on measurement of the radioactivity of the thyroid gland made in 1986 together with a radioecological model and interview data. Approximately 100 histologically confirmed thyroid cancers were detected as a consequence of the first round of screening. The data will enable fitting appropriate dose-response models, which are important in both radiation epidemiology and public health for prediction of risks from exposure to radioactive iodines from medical sources and any future nuclear accidents. Plans are to continue to follow-up the cohort for at least three screening cycles, which will lead to more precise estimates of risk.

Adolescent↗

PubMed2004

Analysis of mortality among Canadian nuclear power industry workers after chronic low-dose exposure to ionizing radiation.

Studies of radiation-associated risks among workers chronically exposed to low doses of radiation are important, both to estimate risks directly and to assess the adequacy of extrapolations of risk estimates from high-dose studies. This paper presents results based on a cohort of 45,468 nuclear power industry workers from the Canadian National Dose Registry monitored for more than 1 year for chronic low-dose whole-body ionizing radiation exposures sometime between 1957 and 1994 (mean duration of monitoring = 7.4 years, mean cumulative equivalent dose = 13.5 mSv). The excess relative risks for leukemia [excluding chronic lymphocytic leukemia (CLL)] and for all solid cancers were 52.5 [95% confidence interval (CI): 0.205, 291] and 2.80 (95% CI: -0.038, 7.13) per sievert, respectively, both associations having P values close to 0.05. Relative risks by dose categories increased monotonically for leukemia excluding CLL but were less consistent for all solid cancers combined. Although the point estimates are higher than those found in other studies of whole-body irradiation, the difference could well be due to chance. Further follow-up of this cohort or the combination of results from multiple worker studies will produce more stable estimates and thus complement the risk estimates from higher-dose studies.

Adult↗

PubMed2004

Analysis of the mortality experience amongst U.S. nuclear power industry workers after chronic low-dose exposure to ionizing radiation.

Workers employed in 15 utilities that generate nuclear power in the United States have been followed for up to 18 years between 1979 and 1997. Their cumulative dose from whole body ionizing radiation has been determined from the dose records maintained by the facilities themselves and the REIRS and REMS systems maintained by the Nuclear Regulatory Commission and the Department of Energy, respectively. Mortality in the cohort from a number of causes has been analyzed with respect to individual radiation doses. The cohort displays a very substantial healthy worker effect, i.e. considerably lower cancer and noncancer mortality than the general population. Based on 26 and 368 deaths, respectively, positive though statistically nonsignificant associations were seen for mortality from leukemia (excluding chronic lymphocytic leukemia) and all solid cancers combined, with excess relative risks per sievert of 5.67 [95% confidence interval (CI) -2.56, 30.4] and 0.506 (95% CI -2.01, 4.64), respectively. These estimates are very similar to those from the atomic bomb survivors study, though the wide confidence intervals are also consistent with lower or higher risk estimates. A strong positive and statistically significant association between radiation dose and deaths from arteriosclerotic heart disease including coronary heart disease was also observed in the cohort, with an ERR of 8.78 (95% CI 2.10, 20.0). While associations with heart disease have been reported in some other occupational studies, the magnitude of the present association is not consistent with them and therefore needs cautious interpretation and merits further attention. At present, the relatively small number of deaths and the young age of the cohort (mean age at end of follow-up is 45 years) limit the power of the study, but further follow-up and the inclusion of the present data in an ongoing IARC combined analysis of nuclear workers from 15 countries will have greater power for testing the main hypotheses of interest.

Cohort Studies↗

PubMed2003

Lung carcinoma after radiation therapy in women treated with lumpectomy or mastectomy for primary breast carcinoma.

BACKGROUND: Prior studies have demonstrated that women who receive adjuvant radiation therapy (RT) after mastectomy for breast carcinoma have an increased risk of a second primary lung carcinoma after 10 years, but, to the authors' knowledge, the risk associated with adjuvant RT after breast-conserving surgery (lumpectomy) has yet to be determined. The purpose of the current study was to confirm and extend earlier findings of the effects of postmastectomy RT on second primary lung carcinoma and to investigate the impact of postlumpectomy RT on second primary lung carcinoma in the same population and to compare the results. METHODS: The authors used data from the population-based Surveillance, Epidemiology, and End Results (SEER) program of the U.S. National Cancer Institute, encompassing approximately 10% of the U.S. population, from 1973 to 1998. Of the women with nonmetastatic invasive breast carcinoma, 194,981 had been treated with mastectomy and 65,560 were treated with lumpectomy. Cox regression analysis was used to estimate the relative risk (RR) of a second primary lung carcinoma among women treated with RT compared with those who received surgery alone as a function of time interval since treatment and laterality for both types of surgery. RESULTS: Although no statistically significant elevation in risk for second primary lung carcinoma prior to 10 years was observed, the authors estimated a RR of 2.06 (95% confidence interval [95% CI], 1.53-2.78) and 2.09 (95% CI, 1.50-2.90) for ipsilateral lung carcinoma at 10-14 years and 15+ years after postmastectomy RT, respectively, whereas no increased risk was observed for the contralateral lung. The excess risk of ipsilateral lung carcinoma after postmastectomy RT was found for all three major histologic subtypes of lung carcinoma (adenocarcinoma, squamous cell carcinoma, and small cell carcinoma). No increased risk of lung carcinoma was observed at 10-14 years after postlumpectomy RT for either lung. CONCLUSIONS: Postmastectomy RT was found to provide a moderate increase in risk for ipsilateral lung carcinoma starting 10 years after exposure; this increased risk is reported to persist to at least 20 years. Postlumpectomy RT does not appear to incur an increased risk. These findings should be reassuring to women treated with either type of RT, but the excess risk in the postmastectomy group should be considered in the choice between treatment options.

Adult↗

PubMedDate not supplied

Association of esophageal adenocarcinoma with other subsequent primary cancers.

PURPOSE: Esophageal adenocarcinoma shares risk factors such as obesity and smoking with other common cancers. The association of esophageal adenocarcinoma with other primary cancers has not been systematically evaluated. The authors used the Surveillance, Epidemiology and End-Results database of the National Cancer Institute to explore the association of esophageal adenocarcinoma with other primary cancers. PATIENTS AND METHODS: All adult patients with esophageal cancers, both adenocarcinoma and squamous cell carcinoma diagnosed between 1973 and 2001, were identified from the Surveillance, Epidemiology, and End-Results database, and standardized incidence rates were calculated for all subsequent primary cancers in these patients. The analysis was reversed to estimate the standardized incidence rate for subsequent primary esophageal cancer after a first primary cancer. RESULTS: In comparison with a standard population, patients with esophageal adenocarcinoma were at higher risk for the development of another subsequent cancer, specifically, cancers of the oral cavity and pharynx, lung and bronchus, and kidney and renal pelvis, and adenocarcinoma of the colon/rectum and pancreas. With squamous cell esophageal cancer, there was an association with tobacco-related cancers such as those of the oral cavity and pharynx, the lung and bronchus, and the breast. There was either no association or even a negative association of esophageal adenocarcinoma with other obesity-related cancers such as breast, uterine, and prostate cancers. CONCLUSIONS: Patients with esophageal adenocarcinoma and squamous cell carcinoma are at increased risk for the development of specific second primary cancers that share smoking as a common risk factor. Esophageal adenocarcinoma does not have a strong association with obesity-related cancers with respect to the relative risk for the development of subsequent primary cancers.

Adenocarcinoma↗