Table 1 Study characteristics of comparative studies evaluating subclinical hypothyroidism and cancer risk and mortality
Study | Study design | n | Data origin | Study period | Population | Definition of SCH |
|---|---|---|---|---|---|---|
Kuijpens 2005 [8] | Prospective cohort | 2738 | The Eindhoven Cancer Registry | 1994–2003 | All women between 47 and 54 years old living in the city of Eindhoven were invited to participate in the Eindhoven perimenopausal osteoporosis study. All women who did not have breast cancer in 1994 were followed | TSH > 6mIU/L and T4 within normal range (8 to 26 pmol/L) |
Hellevik 2009 [15] | Prospective cohort | 29,691 | Nord-Trøndelag Health Study | 1995–2005 | Participants completed questionnaire with thyroid function tests drawn and were followed for cancer incidence, defined using the Cancer Registry of Norway | TSH > 3.5mIU/L |
Razvi 2012 [16] | Retrospective cohort | 4735 | United Kingdom General Practitioner Research Database | 2011–2009 | Patients with incident subclinical hypothyroidism followed for ischemic heart disease and all-cause mortality (cancer mortality also assessed). | TSH 5.01 to 10mIU/L |
Mondul 2012 [60] | Case-control | 1201 | Alpha-Tocophenol, Beta-Carotene Cancer Prevention Study | 1985–1993 | Prostate cancer patients diagnosed 3 years after baseline matched with up to 2 controls | TSH > 3mIU/ L; T4 < 4.6 μg/dL |
Waring 2012 [64] | Prospective study | 1337 | Osteoporotic Fractures in Men Study (MrOs) Cohort | 2000–2011 | Men ≥65 years of age in six clinical centers in the United States | TSH above upper limit of normal and < 10 mU/L |
Fighera 2015 [61] | Retrospective cohort | 622 | Federal University of Parana | 1999–2008 | Patients with subclinical hypothyroidism with thyroid nodules that had thyroidectomy versus fine needle aspiration biopsy | TSH was assessed as a continuous variable |
Boursi 2015 [7] | Nested case-control | 103,044 | The Health Improvement Network (THIN) | 1995–2013 | Case patients identified in THIN with colorectal cancer matched to up to 4 eligible control patients | TSH > 4 mg/dL |
Tseng 2015 [63] | Prospective cohort | 115,746 | Taiwan | 1998–2008 | Patients with no known thyroid disorders on medication treatment that had a health examination in one of 4 private nationwide MJ Health Screening Centers in Taiwan, followed for cancer mortality | TSH 5 to 19.96 mIU/L |
Pinter 2017 [62] | Retrospective cohort | 667 | Medical University of Vienna | 1992–2013 | Patients diagnosed with hepatocellular carcinoma with thyroid function tests, followed for overall survival | Free T4 ≤ 1.66 ng/dL |