Table 1: Summary of available studies evaluating the relationships between diabetes and thyroid cancer.

Study no. [reference]Year authorCountryName of studyStudy designNumber of cases/ Follow-up durationEstimated risk

1 [17]1991 Adami et al.SwedenCancer risk in patients with diabetes mellitusPopulation-based cohort study51,008 patients. Cohort established by identifying diabetic patients during 1965–1983. Complete followup through 1984Women: RR = 1
(95% CI: 0.6–1.8)
Men: RR = 1.3
(95% CI: 0.5–2.8)

2 [18]1997 Wideroff et al.DenmarkCancer incidence in a population-based cohort of patients hospitalized with diabetes mellitus in DenmarkProspective cohort study109,581 diabetics. Cohort established by identifying diabetic patients during 1977–1989. Cohort exit date: date of death or 1993Women: SIR = 1.3
(95% CI: 0.6–2.3)
Men: SIR = 1.2
(95% CI: 0.7–1.8)

3 [19]2006 Inoue et al.JapanThe Japan Public Health Center-based Prospective StudyProspective cohort study46,548 women, 51,223 men
Followed from 1990 through 2003
Women: HR = 1.11
(95% CI: 0.35–3.5)
Men: NA

4 [20]2007 Kuriki et al.JapanHospital based Epidemiologic Research Program at Aichi Cancer Center, JapanCase-control study11,672 incident cancer cases
(5341 men, 6331 women)
47,768 cancer-free controls (14,199 men, 33,569 women)
Women: OR = 0.67
(95% CI: 0.21–2.10)
Men: OR = 1.07
(95% CI: 0.33–3.48)

5 [13]2010 Meinhold et al.USAThe US Radiologic Technologists StudyProspective cohort study69,506 women, 21,207 men
Followed from 1983 through 2006
Women: HR = 1.37
(95% CI: 0.49–3.77)
Men: NA

6 [21]2010 Chodick et al.IsraelDiabetes and risk of incident cancer: a large population-based cohort study in IsraelRetrospective cohort study16,721 DM, 83,874 non-DM
Mean follow-up time: 8 years
Women: HR = 1.61 (95% CI: 0.96–2.69)
Men: HR = 0.72
(95% CI: 0.25–2.04)

7 [22]2011 Aschebrook-Kilfoy et al.USAThe NIH-AARP Diet and Health StudyProspective cohort study200,556 women, 295,992 men
Mean follow-up time: 10 years
Women: HR = 1.54 (95% CI: 1.08–2.20)
Men: HR = 1.11
(95% CI: 0.74–1.66)

8 [23]2012 Kitahara et al.USAPhysical activity, diabetes, and thyroid cancer risk: a pooled analysis of five prospective studiesPooled analysis of five prospective studies, including NIHAARP Diet and Health Study (NIH-AARP), Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO), Breast Cancer Detection and Demonstration Project (BCDDP), Agricultural Health Study (AHS), and US Radiologic Technologists Study (USRT)312,149 women, 362,342 men
Median follow-up time: 10.5 years
Women: HR = 1.19
(95% CI: 0.84–1.69)
Men: HR = 0.96
(95% CI: 0.65–1.42)

Studies no. 5 and 7 were included in the pooled analysis of study 8. CI: confidence interval, HR: Hazard ratio, OR: odds ratio, RR: relative risk, SIR: site-specific standardized incidence ratio, NA: not available.