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Among Individuals Irradiated for Benign Conditions in Childhood, Developing Thyroid Cancer Does Not Affect All-Cause Survival.
Thyroid 2020T

Abstract

Background:

Whether radiation-induced thyroid cancer affects survival rates has not been clearly elucidated. Survival could be affected by the thyroid cancer itself, its treatment, or by being a sign of susceptibility to other cancers. The objective of the current study was to determine if the development of thyroid cancer is associated with a differential survival in radiation-exposed individuals.

Methods:

We conducted a matched prospective cohort mortality follow-up study based on data from a cohort of 4296 individuals who were irradiated predominantly for enlarged tonsils during their childhood (between 1939 and 1962) and were prospectively followed since 1974. The study matched an irradiated subject who developed (was exposed to) thyroid cancer (a "case") and two irradiated subjects, who had not developed (were not exposed to) thyroid cancer ("controls") by the time of case incidence. The two controls were randomly matched to cases by sex, year of birth, age at radiation treatment, and radiation dose. Then, using a stratified Cox analysis, we compared survival time from the date of thyroid cancer diagnosis or time of selection to either date of death or the end of the observation period (December 31, 2016). Vital status and causes of death were determined using the National Death Index (1979-2016), the Social Security Death Index (1974-1979), and study files. Cause of death was categorized as cardiovascular, malignancy, or other.

Results:

A total of 1008 subjects were included in the analysis, including 353 thyroid cancer cases. At the end of the study period, 162 of 655 (24.7%) of individuals without thyroid cancer had died compared with 100 of 353 (28.3%) of the subjects with thyroid cancer. The hazard ratio (HR) for all-cause mortality, comparing the thyroid cancer cases to controls, was close to unity (HR = 1.01 [0.77-1.33]). HRs remained insignificant after eliminating matched sets with microcarcinomas, defined as tumor size <10 mm (HR = 1.39 [0.96-2.03]). Distribution of the causes of death taking into account age and the time of observation differed between cases and controls (p < 0.05). Neither increased cardiovascular-related nor malignancy-related mortality was associated with radiation-induced thyroid cancer.

Conclusions:

Among individuals irradiated for benign conditions in childhood, development of thyroid cancer was not associated with decreased all-cause survival.

Authors+Show Affiliations

Division of Endocrinology, Diabetes and Metabolism, University of Illinois at Chicago, Chicago, Illinois.Division of Cancer Epidemiology & Genetics, Radiation Epidemiology Branch, National Cancer Institute, Bethesda, Maryland.Division of Cancer Epidemiology & Genetics, Biostatistics Branch, National Cancer Institute, Bethesda, Maryland.Division of Endocrinology, Diabetes and Metabolism, University of Illinois at Chicago, Chicago, Illinois.Division of Endocrinology, Diabetes and Metabolism, University of Illinois at Chicago, Chicago, Illinois.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31797741

Citation

Vydro, Leonid, et al. "Among Individuals Irradiated for Benign Conditions in Childhood, Developing Thyroid Cancer Does Not Affect All-Cause Survival." Thyroid : Official Journal of the American Thyroid Association, 2020.
Vydro L, Kitahara CM, Lubin JH, et al. Among Individuals Irradiated for Benign Conditions in Childhood, Developing Thyroid Cancer Does Not Affect All-Cause Survival. Thyroid. 2020.
Vydro, L., Kitahara, C. M., Lubin, J. H., Schneider, A. B., & Mihailescu, D. V. (2020). Among Individuals Irradiated for Benign Conditions in Childhood, Developing Thyroid Cancer Does Not Affect All-Cause Survival. Thyroid : Official Journal of the American Thyroid Association, doi:10.1089/thy.2019.0439.
Vydro L, et al. Among Individuals Irradiated for Benign Conditions in Childhood, Developing Thyroid Cancer Does Not Affect All-Cause Survival. Thyroid. 2020 Jan 16; PubMed PMID: 31797741.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Among Individuals Irradiated for Benign Conditions in Childhood, Developing Thyroid Cancer Does Not Affect All-Cause Survival. AU - Vydro,Leonid, AU - Kitahara,Cari M, AU - Lubin,Jay H, AU - Schneider,Arthur B, AU - Mihailescu,Dan V, Y1 - 2020/01/16/ PY - 2019/12/5/pubmed PY - 2019/12/5/medline PY - 2019/12/5/entrez KW - mortality KW - radiation KW - survival KW - thyroid cancer JF - Thyroid : official journal of the American Thyroid Association JO - Thyroid N2 - Background: Whether radiation-induced thyroid cancer affects survival rates has not been clearly elucidated. Survival could be affected by the thyroid cancer itself, its treatment, or by being a sign of susceptibility to other cancers. The objective of the current study was to determine if the development of thyroid cancer is associated with a differential survival in radiation-exposed individuals. Methods: We conducted a matched prospective cohort mortality follow-up study based on data from a cohort of 4296 individuals who were irradiated predominantly for enlarged tonsils during their childhood (between 1939 and 1962) and were prospectively followed since 1974. The study matched an irradiated subject who developed (was exposed to) thyroid cancer (a "case") and two irradiated subjects, who had not developed (were not exposed to) thyroid cancer ("controls") by the time of case incidence. The two controls were randomly matched to cases by sex, year of birth, age at radiation treatment, and radiation dose. Then, using a stratified Cox analysis, we compared survival time from the date of thyroid cancer diagnosis or time of selection to either date of death or the end of the observation period (December 31, 2016). Vital status and causes of death were determined using the National Death Index (1979-2016), the Social Security Death Index (1974-1979), and study files. Cause of death was categorized as cardiovascular, malignancy, or other. Results: A total of 1008 subjects were included in the analysis, including 353 thyroid cancer cases. At the end of the study period, 162 of 655 (24.7%) of individuals without thyroid cancer had died compared with 100 of 353 (28.3%) of the subjects with thyroid cancer. The hazard ratio (HR) for all-cause mortality, comparing the thyroid cancer cases to controls, was close to unity (HR = 1.01 [0.77-1.33]). HRs remained insignificant after eliminating matched sets with microcarcinomas, defined as tumor size <10 mm (HR = 1.39 [0.96-2.03]). Distribution of the causes of death taking into account age and the time of observation differed between cases and controls (p < 0.05). Neither increased cardiovascular-related nor malignancy-related mortality was associated with radiation-induced thyroid cancer. Conclusions: Among individuals irradiated for benign conditions in childhood, development of thyroid cancer was not associated with decreased all-cause survival. SN - 1557-9077 UR - https://www.unboundmedicine.com/medline/citation/31797741/Among_Individuals_Irradiated_for_Benign_Conditions_in_Childhood,_Developing_Thyroid_Cancer_Does_Not_Affect_All-cause_Survival L2 - https://www.liebertpub.com/doi/full/10.1089/thy.2019.0439?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -