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A Meta-analysis of Individual Participant Data Reveals an Association between Circulating Levels of IGF-I and Prostate Cancer Risk.
Travis, RC, Appleby, PN, Martin, RM, Holly, JMP, Albanes, D, Black, A, Bueno-de-Mesquita, HBA, Chan, JM, Chen, C, Chirlaque, MD, et al
Cancer research. 2016;(8):2288-2300
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Abstract
The role of insulin-like growth factors (IGF) in prostate cancer development is not fully understood. To investigate the association between circulating concentrations of IGFs (IGF-I, IGF-II, IGFBP-1, IGFBP-2, and IGFBP-3) and prostate cancer risk, we pooled individual participant data from 17 prospective and two cross-sectional studies, including up to 10,554 prostate cancer cases and 13,618 control participants. Conditional logistic regression was used to estimate the ORs for prostate cancer based on the study-specific fifth of each analyte. Overall, IGF-I, IGF-II, IGFBP-2, and IGFBP-3 concentrations were positively associated with prostate cancer risk (Ptrend all ≤ 0.005), and IGFBP-1 was inversely associated weakly with risk (Ptrend = 0.05). However, heterogeneity between the prospective and cross-sectional studies was evident (Pheterogeneity = 0.03), unless the analyses were restricted to prospective studies (with the exception of IGF-II, Pheterogeneity = 0.02). For prospective studies, the OR for men in the highest versus the lowest fifth of each analyte was 1.29 (95% confidence interval, 1.16-1.43) for IGF-I, 0.81 (0.68-0.96) for IGFBP-1, and 1.25 (1.12-1.40) for IGFBP-3. These associations did not differ significantly by time-to-diagnosis or tumor stage or grade. After mutual adjustment for each of the other analytes, only IGF-I remained associated with risk. Our collaborative study represents the largest pooled analysis of the relationship between prostate cancer risk and circulating concentrations of IGF-I, providing strong evidence that IGF-I is highly likely to be involved in prostate cancer development. Cancer Res; 76(8); 2288-300. ©2016 AACR.
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Cholesterol and breast cancer risk: a systematic review and meta-analysis of prospective studies.
Touvier, M, Fassier, P, His, M, Norat, T, Chan, DS, Blacher, J, Hercberg, S, Galan, P, Druesne-Pecollo, N, Latino-Martel, P
The British journal of nutrition. 2015;(3):347-57
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Abstract
The objective of the present study was to conduct the first systematic review and meta-analysis of prospective studies investigating the associations between total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C) levels and the risk of breast cancer. Relevant studies were identified in PubMed (up to January 2014). Inclusion criteria were original peer-reviewed publications with a prospective design. Random-effects models were used to estimate summary hazard ratios (HR) and 95% CI. Distinction was made between studies that did or did not exclude cancer cases diagnosed during the first years of follow-up, thereby eliminating potential preclinical bias. Overall, the summary HR for the association between TC and breast cancer risk was 0.97 (95% CI 0.94, 1.00; dose-response per 1 mmol/l increment, thirteen studies), and that between HDL-C and breast cancer risk was 0.86 (95% CI 0.69, 1.09; dose-response per 1 mmol/l increment, six studies), with high heterogeneity (I2= 67 and 47%, respectively). For studies that eliminated preclinical bias, an inverse association was observed between the risk of breast cancer and TC (dose-response HR 0.94 (95% CI 0.89, 0.99), seven studies, I2= 78%; highest v. lowest HR 0.82 (95% CI 0.66, 1.02), nine studies, I2= 81%) and HDL-C (dose-response HR 0.81 (95% CI 0.65, 1.02), five studies, I2= 30 %; highest v. lowest HR 0.82 (95% CI 0.69, 0.98), five studies, I2= 0%). There was no association observed between LDL-C and the risk of breast cancer (four studies). The present meta-analysis confirms the evidence of a modest but statistically significant inverse association between TC and more specifically HDL-C and the risk of breast cancer, supported by mechanistic plausibility from experimental studies. Further large prospective studies that adequately control for preclinical bias are needed to confirm the results on the role of cholesterol level and its fractions in the aetiology of breast cancer.