Men have an increased risk of developing prostate cancer if their blood has high levels of free testosterone and a growth hormone, a conference hears today.
Dr Ruth Travis, an associate professor, and Ellie Watts, a research fellow, at the Nuffield Department of Population Health, University of Oxford, will present their findings at the 2019 NCRI Cancer Conference in Glasgow, Scotland.
The study of 200,452 men, who are part of the UK Biobank project, is one of the first to demonstrate strong evidence of two factors that could be modified to reduce prostate cancer risk.
The men who participated in the project were all free of cancer when they joined the study and were not taking any hormone therapy.
They provided blood samples that were tested for their levels of free testosterone and growth factor-I (IGF-I) and a cohort of 9,000 of men gave a second blood sample at a later date, to help the researchers account for natural fluctuations in hormone levels.
The men were followed for an average of six to seven years during which time there were 5,412 prostate cancer cases and 296 deaths from the disease.
The researchers found that for every increase of five nanomoles in the concentration of IGF-I per litre of blood (5 nmol/L), men were 9% more likely to develop prostate cancer.
They also established that for every increase of 50 picomoles of free testosterone per litre of blood (50 pmol/L), there was a 10% increase in prostate cancer risk.
Looking at the whole population, the researchers say their findings correspond to a 25% greater risk in men who have the highest levels of IGF-I, compared to those with the lowest, while men with the highest ‘free’ testosterone levels face a 18% greater risk of prostate cancer, compared to those with the lowest levels.
Dr Travis said: “This type of study can’t tell us why these factors are linked, but we know that testosterone plays a role in the normal growth and function of the prostate and that IGF-I has a role in stimulating the growth of cells in our bodies.
“What this research does tell us is that these two hormones could be a mechanism that links things like diet, lifestyle and body size with the risk of prostate cancer. This takes us a step closer to strategies for preventing the disease.”
Abstract number 2904, ‘Serum hormones and prostate cancer incidence and mortality in UK Biobank’, Ruth Travis et al., poster presentation, area 1 number 14, 16.02 hrs, Sunday 3 November.
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