Purpose: Emerging evidence suggests that adiponectin may play a protective role in tumor progression and prognosis. However, available evidence in prostate cancer is conflicting. Therefore, we carried out a meta-analysis to evaluate the role of circulating adiponectin and prostate cancer.
Methods and results: An extensive search was performed on Google, PubMed, Elsevier Science and Springer from the date of the inception of those services to December 2013. Eleven studies with 2,504 patients and 3,565 controls concerning this association were included in our analysis. Standard mean difference (SMD) with 95% confidence intervals (95% CIs) was used to estimate this association. The pooled analysis showed that circulating adiponectin concentrations were lower in patients with prostate cancer than controls, with a pooled SMD of -0.893 μg/mL (95% CI, -1.345 to -0.440, p=0.000). Dose-response relationships between concentrations of adiponectin and risk of prostate cancer were evaluated. We found that decreased concentrations of adiponectin were associated with a significantly greater risk of prostate cancer (p for nonlinearity = 0.043).
Conclusions: The results of our analysis indicated that concentration of adiponectin in cancer patients was significantly lower than in controls. Thus, adiponectin may serve as a potential biomarker for early diagnosis of this disease. We also found that decreased concentration of adiponectin was associated with a significantly greater risk of prostate cancer. However, more studies in future, especially larger, prospective studies, are needed to confirm this association with underlying biological mechanisms.