Two new studies, reported today, show how the development of breast cancer is linked to the growth hormone called insulin-like growth factor-1.
Both studies used information from the UK Biobank study. The first, based at the International Agency for Research on Cancer (IARC), Lyon, France, looked at links between levels of insulin-like growth factor-1 in the blood and disease risk in 206,263 women.
The second, based at the University of Oxford, UK, used Mendelian randomisation analysis to examine 265 gene variants (single nucleotide polymorphisms) and showed that this link with insulin-like growth factor-1 is likely to be causal.
This study also suggested that four single nucleotide polymorphisms for insulin-like growth factor-binding protein-3 may control the availability of insulin-like growth factor-1.
Both appear today (11 March) in Annals of Oncology.
Dr Neil Murphy of the International Agency for Research on Cancer said: “We found that higher levels of insulin-like growth factor-1 circulating in the blood, as determined by blood measurements and genetic markers, were related to higher breast cancer risk.
“These results support a probable causal role of the insulin-like growth factor pathway in breast cancer development.”
Dr Marc Gunter, also at the International Agency for Research on Cancer, added: “To our knowledge, this is largest single study and the first Mendelian randomisation study to examine the relationship between insulin-like growth factor-1 and breast cancer.
“Importantly, our Mendelian randomisation analyses yielded strikingly similar positive associations between insulin-like growth factor-1 and breast cancer as those found in our observational analyses.
“Taken together, these results provide the strongest evidence to date for a causal role of the insulin-like growth factor pathway in breast cancer development and suggest that altering levels through diet and lifestyle or pharmacological means may be an effective strategy in the primary prevention of breast cancer.”
Murphy, N. et al. Insulin-like growth factor-1 (IGF-1), insulin growth factor-binding protein-3 (IGFBP-3) and breast cancer risk: observational and Mendelian randomization analyses with 430,000 women. Annals of Oncology 11 March 2020; doi: 10.1016/j.annonc.2020.01.066
https://www.annalsofoncology.org/article/S0923-7534(20)36019-1/fulltext
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