Association between height and thyroid cancer risk: A meta-analysis of prospective cohort studies

While several epidemiological studies have investigated the relationship between height and risk for thyroid cancer, the results were inconsistent. In the present study, a systematic review and meta-analysis of prospective cohort studies was conducted to assess the impact of height on thyroid cancer risk. Online databases were searched up to December 30, 2014, for prospective cohort studies on the association between height and thyroid cancer risk. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random-effects model of meta-analysis. In all, 11 articles were included in this meta-analysis, including 15 prospective cohort studies, containing 6,695,593 participants and 7,062 cases of thyroid cancer. By comparing the highest versus the lowest categories of height, we reported that risk of thyroid cancer was increased with height in both men (summary RR=1.40, 95%CI 1.09-1.78, p=0.008) and women (summary RR=1.54, 95%CI 1.30-1.83, p<0.001). The summary RR of thyroid cancer per 5-cm increase in height was 1.16 (95%CI 1.09-1.23, p<0.001). The results were similar among men (per 5-cm increase RR=1.13, 95%CI 1.03-1.23, p=0.011) and women (per 5-cm increase RR=1.18, 95%CI 1.10-1.27, p<0.001). No obvious risk of publication bias was observed. Our meta-analysis provides strong evidence for a dose-response relationship between height and risk of thyroid cancer in both men and women. What's new? The taller a person is, the greater his or her risk for thyroid cancer may be, although not all studies on the subject have reached that same conclusion. To gain a clearer picture of the relationship between height and thyroid cancer, the present meta-analysis took into consideration data from 15 prospective cohort studies. The findings of the analysis corroborate the existence of an association, whereby thyroid cancer risk increases with increasing height, in both men and women. Although the mechanistic basis for the association awaits elucidation, pathways centering on insulin-like growth factor-1 (IGF-1), which influences growth, are implicated.