Plasma adiponectin and soluble leptin receptor and risk of colorectal cancer: A prospective study

Adipokines are adipocyte-secreted hormones that may mediate the etiologic link between obesity and colorectal cancer; however, the evidence from large prospective studies is limited. We prospectively evaluated the association of plasma adiponectin and soluble leptin receptor (sOB-R) with colorectal cancer risk within the Nurses' Health Study (1990-2008) and the Health Professionals Follow-up Study (1994-2008) among 616 incident colorectal cancer cases and 1,205 controls selected using risk-set sampling and matched on age and date of blood draw. In unconditional logistic regression with adjustment for matching factors and multiple risk factors, plasma adiponectin was significantly associated with reduced risk of colorectal cancer among men, but not among women. Compared with men in the lowest quartile of adiponectin, men in the highest quartile had a relative risk (RR) for colorectal cancer of 0.55 [95% confidence interval (CI), 0.35-0.86; P_trend = 0.02]. The corresponding RR in women was 0.96 (95% CI, 0.67-1.39; P_trend = 0.74). Plasma sOB-R was not associated with overall colorectal cancer risk in either men or women. A significant heterogeneity was noted in the association between sOB-R and colorectal cancer by subsite in women (P_{heterogeneity} = 0.004); sOB-R was significantly associated with increased risk of rectal cancer but not colon cancer. These findings support a role for adiponectin in colorectal carcinogenesis in men. Further studies are warranted to confirm these associations and elucidate potential underlying mechanisms.