Background/Aims: Insulin-like growth factor-1 (IGF-1) has an important role in cells' proliferation, differentiation and apoptosis, and it may be involved in carcinogenesis. Several epidemiological studies assessed the association between circulating IGF-1 level and ovarian cancer risk, but there was still no conclusive finding. Methods: A meta-analysis of published studies was performed to assess the association between circulating IGF-1 level and ovarian cancer risk. The summary odds ratio (OR) with 95% confidence interval (95%CI) was calculated through meta-analysis to evaluate the strength of the association. Results: Five eligible studies were included into the meta-analysis, which involved a total of 2,028 cases of ovarian cancer and 4,625 controls. Meta-analysis of total 5 studies showed that high circulating IGF-1 level was correlated with decreased risk of ovarian cancer (OR = 0.84, 95%CI 0.74-0.97, P = 0.013). After adjusting for heterogeneity, high circulating IGF-1 level was still correlated with decreased risk of ovarian cancer (OR = 0.83, 95%CI 0.72-0.95, P = 0.007). Subgroup analysis by age showed that circulating IGF-1 level was not correlated with ovarian cancer risk in women both less than 55 years and more than 55 years. However, after adjusting for heterogeneity, high circulating IGF-1 level was correlated with decreased ovarian cancer risk in women less than 55 years (OR = 0.82, 95%CI 0.72-0.94, P = 0.004). Conclusion: Our meta-analysis suggests that high circulating IGF-1 level may be correlated with decreased ovarian cancer risk, especially in women less than 55 years. More studies are needed to further assess the association between circulating IGF-1 level and ovarian cancer risk in the future.
Tea and coffee drinking and ovarian cancer risk: results from the Netherlands Cohort Study and a meta-analysis
