Research being presented at the National Cancer Research Institute conference in Glasgow this weekend suggests circulating hormone concentrations are associated with risk for prostate cancer development.
Although insulin-like growth factor-I (IGF-I) and testosterone have previously been implicated in prostate cancer development and progression, these associations are not fully understood. As modifiable risk factors for prostate cancer are not well established, the team of researchers investigated the associations of circulating concentrations of IGF-I, free and total testosterone and sex hormone-binding globulin (SHBG) with prostate cancer incidence and mortality in a British cohort.
Data from approximately 200,000 male UK Biobank participants were included. Participants were free from cancer and not receiving hormone therapy at recruitment and had hormone measurements taken at baseline. Free testosterone was calculated from measured total testosterone and binding protein concentrations. Hazard ratios (HRs) were corrected for regression dilution using repeat hormone measurements from a subsample of up to 7794 men.
After a mean follow-up of 6.9 years, 5412 men were diagnosed with prostate cancer and 296 had died from the disease.
Higher circulating IGF-I was associated with an elevated risk of prostate cancer diagnosis (HR per 1 standard deviation [SD] increase, 1.11; 95% CI, 1.07-1.15) and prostate cancer mortality (HR per 1 SD increase, 1.17; 95% CI, 1.01-1.36).
Higher free testosterone was associated with an elevated risk of incident prostate cancer (HR per SD increase, 1.14; 95% CI, 1.08-1.20).
Higher SHBG was associated with a lower risk (HR per SD increase, 0.93; 95% CI, 0.90-0.96).
Neither free testosterone nor SHBG was associated with prostate cancer mortality.
Total testosterone concentration was not associated with prostate cancer incidence or mortality.
The authors say the findings support the hypothesised roles of IGF-I and free testosterone in prostate cancer development. Future research is planned to examine associations by tumour characteristics.