Each year in the UK, nearly 50,000 men are diagnosed with prostate cancer, making it the most common cancer in males. Of these, more than 10,000 men die per year from the disease (Cancer Research UK). Established risk factors for prostate cancer include age, family history, ethnicity and genetic factors. Although there is substantial international variation in prostate cancer incidence, there are no well-established modifiable risk factors.
There is some evidence that testosterone, folate, vitamin B12, iron, and chronic inflammation are associated with prostate cancer risk, and these factors are also associated with changes in blood count parameters (red blood cell, white blood cell and platelets). Therefore, in order to understand more about prostate cancer aetiology, blood test parameters can be used as surrogate markers for these possible risk factors.
The UK Biobank is a national prospective cohort of 500,000 participants established to improve the “prevention, diagnosis and treatment of a wide range of serious and life-threatening illnesses’. Health data and blood samples are provided anonymously by the participants to enable research. A full blood count has been recorded for the entire cohort (230,000 men) and repeat measurements are available for ~9000 men, making it an ideal setting in which to study the association between any changes in routine blood test results and risk of prostate cancer incidence and mortality.
In this paper in Cancer Epidemiology, Biomarkers and Prevention, Dr Eleanor Watts (Cancer Epidemiology Unit, Nuffield Department of Population Health) and colleagues analysed UK Biobank blood count data from over 200,000 men followed for an average of 6.8 years and found that higher total red blood cell and platelet counts were associated with a higher risk of prostate cancer incidence but not mortality. By contrast, measures of red blood cell volume were associated with lower prostate cancer risk. Higher white blood cell counts were associated with an increased risk of prostate cancer mortality but not diagnosis. These observations are consistent with the proposed roles of testosterone, dietary factors and inflammation in prostate cancer development. Whilst further analysis is required to investigate causality in these relationships, this work has used a unique data resource to produce the most reliable estimations to date of blood count associations with prostate cancer risk.