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- Lukanova, Annekatrin, et al.
(författare)
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Nonlinear relationship of insulin-like growth factor (IGF)-I and IGF-I/IGF-binding protein-3 ratio with indices of adiposity and plasma insulin concentrations (Sweden).
- 2002
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Ingår i: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 13:6, s. 509-516
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: In this study we test the hypothesis of a nonlinear relationship of IGF-I with indices of body fat such as body mass index (BMI), insulin, and leptin.METHODS: The controls used in three case-control cancer studies nested in the Northern Sweden Health and Disease Cohort, were combined for this analysis. Measurements of plasma IGF-I, IGFBP-3, insulin, and leptin were available for 445 men and 391 women.RESULTS: In both men and women we found the highest mean IGF-I levels in subjects with BMI between 24 and 26. IGF-I concentrations decreased toward BMI < or = 20 and BMI > 30 in men; however, the results for women did not reach statistical significance. The molar ratio of IGF-I/IGFBP-3 showed a similar profile to that of IGF-I, although much less pronounced. The observed peak mean IGF-I levels in the second quintiles of insulin and leptin in men supported these findings. No significant variation of mean IGF-I levels across quintiles of insulin and leptin were observed in women.CONCLUSIONS: The results of this study provide evidence that IGF-I plasma concentrations vary substantially over a wide range of body weight and that the relationship is nonlinear.
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| 2. |
- Stattin, Pär, et al.
(författare)
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Obesity and colon cancer : does leptin provide a link?
- 2004
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 109:1, s. 149-152
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Tidskriftsartikel (refereegranskat)abstract
- Obesity, a risk factor for colorectal cancer, is associated with elevated serum levels of leptin, the adipocyte-derived hormone, and insulin. Experimental and epidemiologic studies have indicated a role for insulin in the pathogenesis of colon cancer, and recent experimental studies have suggested a similar role for leptin. In a case-control study nested in the Janus Biobank, Norway, we measured serum levels of leptin and C-peptide (a marker of pancreatic insulin secretion) in cryopreserved prediagnostic sera from men (median age, 45 years) who were diagnosed with cancer of the colon (n = 235) or rectum (n = 143) after blood collection (median time, 17 years), and among 378 controls matched for age and date of blood collection. Conditional logistic regression analyses showed an approximately 3-fold increase in colon cancer risk with increasing concentrations of leptin up to an odds ratio (OR) of 2.72 (95% CI = 1.44-5.12) for top vs. bottom quartile (p(trend) = 0.008). The corresponding OR for C-peptide was 1.81 (95% CI = 0.67-4.86; p(trend) = 0.19). The risk estimates remained unchanged after mutual adjustment. No association of hormone levels with rectal cancer risk was found. Reproducibility of hormone measurements assessed by intraclass coefficients (ICCs) for paired samples taken 1 year apart was high for leptin (ICC = 0.82) but lower for C-peptide (ICC = 0.30). Our results suggest that leptin is a risk factor for colon cancer, and that leptin may provide a link between obesity and colon cancer. Leptin may be directly involved in colon tumorigenesis or it may serve as a sensitive and robust marker of an obesity-induced adverse endocrine environment. Only weak support for an association of insulin with colon cancer was found.
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