Association between obesity-related adipokines and colorectal cancer:A case-control study and meta-analysis

AIM: To examine the association between obesity-related adipokines (adiponectin, leptin, resistin, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) and colorectal cancer (CRC) risk.

AIM:To examine the association between obesityrelated adipokines(adiponectin,leptin,resistin,interleukin-6(IL-6),and tumor necrosis factor-α(TNF-α)and colorectal cancer(CRC)risk.METHODS:Serum levels of adipokines were measured in 100 CRC patients and age-and sex-matched controls for the data analysis.Unconditional logistic regression models were used for estimating ORs and95%CIs related to each adipokine.For the metaanalysis,studies published before July 2013 available on Medline/PubMed and EMBASE were retrieved.The analysis included a total of 17 relevant studies(including the present case-control study):nine studies on adiponectin and eight on leptin.The effect sizes of ORs and 95%CIs were estimated using RevMan 5.1.Heterogeneity was evaluated using Cochran’s Q-test and I2 statistics.RESULTS:Among the five adipokines,only resistin levels were significantly higher in cases than in controls(P<0.001).The case-control study results showed no association between adiponectin and CRC and a negative association between leptin and CRC.However,the results of the meta-analysis showed a significant inverse association between adiponectin and CRC(OR=0.91,95%CI:0.83-1.00,P=0.04)and no association between CRC and leptin.After stratification by study design,an inverse association between adiponectin and CRC was observed in prospective studies only(OR=0.90,95%CI:0.82-0.99,P=0.03),whereas the association between leptin and CRC was inconsistent(prospective studies:OR=1.14,95%CI:1.02-1.27,P=0.02 and retrospective studies:OR=0.47,95%CI:0.29-0.74,P=0.001).The associations of resistin and TNF-αwith CRC risk were positive,but no association was observed for IL-6.CONCLUSION:Our results suggest a negative association of leptin,positive associations of resistin and TNF-α,and null associations of adiponectin and IL-6with CRC.However,further studies with larger number of prospective approaches are needed.