Research Findings

Incidence Studies - Thyroid Cancer

Occupational radiation exposure and thyroid cancer incidence in a cohort of U.S. radiologic technologists, 1983-2013 (2018)
 Thyroid cancer (476 cases) risk among 89,897 radiologic technologists was not related to estimated occupational absorbed radiation dose to the thyroid gland.
Assessment of thyroid cancer risk associated with radiation dose from personal diagnostic examinations in a cohort study of US radiologic technologists, followed 1983-2014 (2018)
 Thyroid cancer risk associated with radiation dose from personal diagnostic examinations was evaluated in 76,415 U.S. radiologic technologists who were cancer-free other than non-melanoma skin cancer at the first cohort questionnaire completed. Dose-response risks were positive but not statistically significant for all thyroid cancer (excess relative risk (ERR)/Gy=2.29; 95% CI -0.91-7.01; 414 cases) and papillary thyroid cancer (ERR/Gy=4.15; 95% CI -0.39-11.27; 275 cases).
Prospective Study of Ultraviolet Radiation Exposure and Thyroid Cancer Risk in the United States (2017)
 Higher UVR exposure at ages 40 and older, but not at younger ages, was associated with reduced risk of thyroid cancer (153 cases) among 44,039 radiologic technologists. Risk was not related to average lifetime UVR exposure.
Anthropometric factors and thyroid cancer risk by histological subtype: pooled analysis of 22 prospective studies (2016)
 A pooled analysis of 22 prospective studies revealed increased thyroid cancer incidence and mortality risks with height, waist circumference, young adult BMI, and adulthood weight gain.
Thyroid cancer and nonsteroidal anti-inflammatory drug use: A pooled analysis of patients over 40 years of age (2015)
 A pooled analysis of 3 prospective cohorts revealed that thyroid cancer risk was not associated with aspirin or non-aspirin NSAID use; risk was increased in women and with obesity, and reduced with smoking and alcohol consumption.
A prospective study of medical diagnostic radiography and risk of thyroid cancer (2013)
 Thyroid cancer risks associated with personal diagnostic x-ray procedures (cervical spine, skull, other head and neck, thoracic spine, angiogram, dental, mammogram, upper gastrointestinal, barium swallow, chest, lumbar spine) were evaluated in 75,494 radiologic technologists (251 thyroid cancer cases). Risk was increased with number of dental x-rays but was not associated with other x-ray procedures, many of which conferred much larger doses to the thyroid.
Cigarette smoking, alcohol intake, and thyroid cancer risk: A pooled analysis of five prospective cohorts in the United States (2012)
 Thyroid cancer risks associated with cigarette smoking and alcohol intake were examined in a pooled study of five prospective cohorts that included 1,003 men and women with thyroid cancer. Cigarette smoking characteristics (current vs. never, intensity, duration, and pack-years), as well as alcohol consumption (>7 drinks per week vs. 0), were associated with reduced thyroid cancer risks.
Physical activity, diabetes, and thyroid cancer risk: a pooled analysis of five prospective studies (2012)
 Thyroid cancer risk was not associated with a history of diabetes in a pooled study of five prospective cohorts that included 818 men and women with thyroid cancer. Risk increased with increasing physical activity in overweight or obese individuals, but was not related to physical activity in those with normal weight.
Obesity and thyroid cancer risk among U.S. men and women: a pooled analysis of five prospective studies (2011)
 Risk of thyroid cancer increased with increasing BMI in both men and women in a pooled analysis of 388 female and 768 male thyroid cancer cases from five cohort studies. BMI-related risks were not modified by other thyroid cancer risk factors, including education, race, marital status, cigarette smoking, and alcohol consumption.
Non-radiation risk factors for thyroid cancer in the US Radiologic Technologists Study (2010)
 Among 90,713 U.S. radiologic technologists, 282 incident thyroid cancers were diagnosed during 1983-2006. Elevated thyroid cancer risk was associated with benign thyroid conditions, benign breast disease, asthma, and higher body mass index. Current cigarette smokers were at decreased risk of thyroid cancer. Reproductive factors, other medical conditions, alcohol intake, and physical activity were not related to risk.
Thyroid cancer and employment as a radiologic technologist (2006)
 We evaluated thyroid cancer risk associated with employment as a radiologic technologist in two groups of technologists: (a) those who were free of thyroid cancer at the first (baseline) survey in the mid-1980s and completed a second survey in the mid-1990s (148 thyroid cancers); and (b) those who were free of thyroid cancer for at least two years after certification and were followed to the baseline survey (121 thyroid cancers). A history of holding patients for x-rays at least 50 times was associated with a statistically significant 50% excess risk of thyroid cancers that occurred after the baseline survey; however, year began working as a radiologic technologist, number of years worked in total and by decade, years performing various procedures, and employment under age 20 were not related to thyroid cancer after the baseline survey. For thyroid cancers diagnosed before the baseline survey, risk increased with earlier year began working and was significantly elevated among those who worked 5 or more years before 1950.