TUESDAY, March 17, 2020 (HealthDay News) — There seems to be a causal association between circulating insulin-like growth factor-1 (IGF-1) concentrations and breast cancer, according to a study published online March 10 in the Annals of Oncology.

Neil Murphy, Ph.D., from the International Agency for Research on Cancer in Lyon, France, and colleagues examined the association between circulating IGF-1 concentrations and incident breast cancer risk in 206,263 women from the U.K. Biobank. In a subsample of 6,711 women, hazard ratios were corrected for regression dilution using repeat IGF-1 measures. In addition, in Mendelian randomization (MR) analyses, genetic variants associated with IGF-1 and IGF-binding protein-3 (IGFBP-3) levels were identified and their association with breast cancer was analyzed using data for 122,977 cases and 105,974 controls.

The researchers identified 4,360 incident breast cancer cases after a median follow-up of 7.1 years in the U.K. Biobank. Higher IGF-1 concentrations were associated with an increased risk for breast cancer in multivariable-adjusted models (hazard ratio per 5-nmol/L increment of IGF-1, 1.11; 95 percent confidence interval [CI], 1.07 to 1.16). In the MR analyses, greater breast cancer risk was seen in association with a 5-nmol/L increment in genetically predicted IGF-1 concentration (odds ratio, 1.05; 95 percent CI, 1.01 to 1.10; P = 0.02); a similar effect estimate was seen for estrogen-positive tumors, but not for estrogen-negative tumors. There was no association seen between genetically predicted IGFBP-3 concentrations and breast cancer risk (odds ratio per 1-standard deviation increment, 1.00; 95 percent CI, 0.97 to 1.04; P = 0.98).

“This result suggests that pharmacological or lifestyle interventions targeting the IGF pathway may be beneficial in preventing breast tumorigenesis,” the authors write.

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