Reproductive Factors but Not Hormonal Factors Associated with Thyroid Cancer Risk: A Systematic Review and Meta-Analysis.
Many studies have investigated the association between hormonal and reproductive factors and thyroid cancer risk but provided contradictory and inconclusive findings. This review was aimed at precisely estimating this association by pooling all available epidemiological studies. 25 independent studies were retrieved after a comprehensive literature search in databases of PubMed and Embase. Overall, common hormonal factors including oral contraceptive and hormone replacement therapy did not alter the risk of thyroid cancer. Older age at menopause was associated with weakly increased risk of thyroid cancer in overall analysis (RR = 1.24, 95% CI 1.00-1.53, P = 0.049); however, longer duration of breast feeding was related to moderately reduced risk of thyroid cancer, suggested by pooled analysis in all cohort studies (RR = 0.7, 95% CI 0.51-0.95, P = 0.021). The pooled RR in hospital-based case-control studies implicated that parous women were more susceptible to thyroid cancer than nulliparous women (RR = 2.30, 95% CI 1.31-4.04, P = 0.004). The present meta-analysis suggests that older age at menopause and parity are risk factors for thyroid cancer, while longer duration of breast feeding plays a protective role against this cancer. Nevertheless, more relevant epidemiological studies are warranted to investigate roles of hormonal and reproductive factors in thyroid carcinogenesis.
Reproductive Center, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Yijuan
Y
Cao
Department of Anesthesia, People's Hospital of Zhucheng, Zhucheng 262200, China.
Zengyan
Z
Wang
Reproductive Center, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Juan
J
Gu
Reproductive Center, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Fangfang
F
Hu
Reproductive Center, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Yujuan
Y
Qi
Reproductive Center, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Qianqian
Q
Yin
Reproductive Center, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Qingqing
Q
Sun
Reproductive Center, The Affiliated Hospital of Weifang Medical University, Weifang 261000, China.
Guotao
G
Li
Department of General Surgery, Central Hospital of Xuzhou, Affiliated Xuzhou Hospital of Southeast University, Xuzhou 221009, China.
Bin
B
Quan
D000367:Age Factors; D063646:Carcinogenesis; D005260:Female; D006728:Hormones / Q000378:metabolism*; D006801:Humans; D008593:Menopause / Q000378:metabolism; D010298:Parity / Q000502:physiology; D011247:Pregnancy; D039781:PubMed; D012098:Reproduction / Q000502:physiology; D012307:Risk Factors; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000473:pathology
D006728:Hormones