METHODS: We analyzed data from 767 prostate cancer cases and 767 matched controls nested within the European Prospective Investigation into Cancer and Nutrition cohort, with an average of 14-years (interquartile range = 2.9) follow-up. Matching variables were study center, length of follow-up, age, and time of day and fasting duration at blood collection. Circulating free IGF-I concentration was measured in serum samples collected at recruitment visit (mean age 55 years old; standard deviation = 7.1) using an enzyme-linked immunosorbent assay (ELISA). Conditional logistic regressions were performed to examine the associations of free IGF-I with risk of prostate cancer overall and subdivided by time to diagnosis (≤ 14 and > 14 years), and tumor characteristics.
RESULTS: Circulating free IGF-I concentrations (in fourths and as a continuous variable) were not associated with prostate cancer risk overall (odds ratio [OR] = 1.00 per 0.1 nmol/L increment, 95% CI: 0.99, 1.02) or by time to diagnosis, or with prostate cancer subtypes, including tumor stage and histological grade.
CONCLUSIONS: Estimated circulating free IGF-I was not associated with prostate cancer risk. Further research may consider other assay methods that estimate bioavailable IGF-I to provide more insight into the well-substantiated association between circulating total IGF-I and subsequent prostate cancer risk.
方法:我们分析了来自767例前列腺癌病例和767例配对对照的欧洲癌症和营养队列前瞻性调查的数据。平均14年(四分位距=2.9)随访。匹配变量是研究中心,随访时间,年龄,以及一天中的时间和采血时的禁食持续时间。使用酶联免疫吸附测定(ELISA)测量招募时收集的血清样品中的循环游离IGF-I浓度(平均年龄55岁;标准偏差=7.1)。进行条件逻辑回归以检查游离IGF-I与前列腺癌总体风险的关联,并按诊断时间(≤14和>14年)细分。和肿瘤特征。
结果:循环游离IGF-I浓度(占四分之一,作为连续变量)与前列腺癌总体风险无关(比值比[OR]=1.00每0.1nmol/L增量,95%CI:0.99,1.02)或按诊断时间计算,或前列腺癌亚型,包括肿瘤分期和组织学分级。
结论:估计的循环游离IGF-I与前列腺癌风险无关。进一步的研究可以考虑评估生物可利用的IGF-I的其他测定方法,以提供对循环总IGF-I与随后的前列腺癌风险之间充分证实的关联的更多见解。