A growth hormone could play a role in the development of breast cancer, according to research.
Scientists believe the substance, called insulin-like growth factor-1 (IGF-1), to be “a likely cause” of the disease after finding an association between higher IGF-1 levels in the blood and the development of breast cancer.
According to the researchers, the findings, published in the cancer journal Annals of Oncology, suggest altering IGF-1 levels through diet and lifestyle or medication could be an “effective strategy” in preventing breast cancer at an early stage.
Dr Neil Murphy, a scientist at the International Agency for Research on Cancer (IARC) in France – one of the study authors – said: “We found that higher levels of IGF-1 circulating in the blood, as determined by blood measurements and genetic markers, were related to higher breast cancer risk.”
Dr Marc Gunter, a scientist and head of the nutrition and metabolism section at IARC, who was also involved in the study, added: “These results provide the strongest evidence to date for a causal role of the IGF-pathway in breast cancer development, and suggest that altering IGF-1 levels through diet and lifestyle or pharmacological means may be an effective strategy in the primary prevention of breast cancer.”
Previous studies have shown IGF-1 to encourage the growth of cancer cells.
Researchers from IARC and the Cancer Epidemiology Unit at the University of Oxford conducted two studies to investigate the role of IGF-1 in breast cancer development.
The first looked at the associations between levels of IGF-1 in the blood and the risk of the disease developing in 206,263 women enrolled in the UK Biobank, an online database of 500,000 people and their medical conditions.
The team found those with highest IGF-1 concentrations in the blood, the top 20%, had a 1.24-fold increased chance of developing breast cancer compared to those in the bottom 20%.
The second study, which looked at 122,977 cases of breast cancer and 105,974 women without cancer, used a technique called Mendelian randomisation, which takes into account a person’s genetic code along with other available data to identify health risks, to analyse data from 265 gene variants known to be associated with IGF-1 concentrations.
According to the researchers, the risk of breast cancer increased by 1.05 for for every additional 5 nanomoles per litre of blood (nmol/L) of genetically-predicted IGF-1.
While drugs to target the IGF-1 system have been developed, scientists believe it may be possible to modify IGF-1 concentrations in the blood through changes in a person’s diet.
Dr Gunter said: “Our next step is to gain a fuller understanding of which lifestyle practices can alter IGF-1 concentrations and, in turn, the chances of breast cancer developing.”