This men’s health week, National Institute for Health Research Biomedical Research Centre and Integrative Cancer Epidemiology Programme PhD student Meda Sandu outlines findings from research on how we can best prevent and treat prostate cancer.
Prostate cancer (PCA) is the second most common cancer in the adult population in the UK, with over 47, 000 new cases being diagnosed each year. Over 400, 000 people assigned male at birth live with or after a diagnosis of PCA. Localised PCA is cancer that is confined in the prostate gland and has not spread to other organs. Localised PCA often grows slowly, may not give any symptoms and/or require treatment. However, occasionally this type of cancer is aggressive in nature, can spread fast and will require treatment. Patients who undergo radical treatment, such as surgery and radiotherapy, often report side effects which significantly impact their wellbeing and enjoyment of life, such as urinary and bowel incontinence, low libido, erectile dysfunction, fatigue, mood swings. Our research looks at lifestyle interventions that may help prevent PCA, as well as identifying cases when treatment may be delayed, in an attempt to best support outcomes for people with PCA.
How does treatment choice affect survival?
In the ProtecT study people were randomised to various treatments or active surveillance where no treatment is given but the patient is regularly followed-up. The study found similar chances of surviving localised PCA, with those in the active surveillance group only having a very small decrease in survival compared to the other groups. This prompted a spur of research in identifying modifiable factors which could delay PCA progression and therefore avoid unnecessary treatment.
One of the aims of our research is to look at dietary and lifestyle changes that are acceptable and achievable to PCA patients, which could reduce PCA risk and progression. These could prevent PCA or, for those who have already been diagnosed with localised disease, delay treatment and therefore avoid the associated side effects.
Dietary and physical activity interventions in people with PCA
In the PrEvENT feasibility randomised controlled trial, patients who underwent prostate removal surgery were randomly assigned to both a dietary and a physical activity intervention. The dietary intervention consisted of either:
- a lycopene supplement, which is an antioxidant found in tomatoes and has been previously be suggested to be protective for PCA
- eating 5 portions of fruit and vegetable per day and replacing dairy milk with a vegan option (soy, almond, oat, coconut etc)
- continue as normal.
The physical activity intervention asked participants to do 30 minutes of brisk walking five times a week.
For each intervention, we looked at the change in metabolites, which are very small molecules found in blood that reflect metabolic patterns, a very useful measure in diseases where there are metabolic changes, such as cancer. We found that eating more fruit and vegetables and decreasing dairy changed blood metabolite levels. Of particular interest was the change in pyruvate levels, a metabolite used as fuel in the pathway of cancer cell proliferation. This suggests that our interventions could lead to less energy being available to the proliferation of cancerous cells, which could lead to lower PCA risk and progression.
Can we predict which PCA cases do not need treatment?
A second aim of my research is to identify blood markers that can help distinguish disease that is unlikely to cause problems from aggressive disease that will advance rapidly and require treatment. We looked at the ProtecT trial and provisionally identified metabolites that could help predict PCA progression. This would allow clinicians to more accurately decide if the patient should take up treatment or if active surveillance would be appropriate.
Patients diagnosed with localised PCA have 96% chance of surviving 15 years after diagnosis. However, PCA risk factors have yet to be conclusively identified. In addition, the diagnosing techniques are invasive and there is uncertainty around which localised cases are likely to advance. More research is therefore needed to establish potential risk factors which could help prevent PCA, and blood-based markers that could predict the aggressiveness of localised PCA cases. We are also looking at the relationship between PCA risk and progression and blood DNA methylation markers, which allow cells to control the expression of genes and have previously been suggested to be responsive to both environmental factors and causes of cancer and could help us better understand the aetiology of PCA.
So what does this mean for people with prostate cancer?
Although more research is required as our studies were small and did not aim to have definitive answers, we did find some evidence to suggest that some lifestyle changes, namely increased fruit and vegetable consumption and replacing milk with non-dairy options and walking 30 minutes a day, 5 times a week are acceptable to PCA patients and that these interventions may have promising effects on blood metabolites. Identifying lifestyle factors which may have a protective role could help prevent PCA cases. Our research also identified metabolites which may help predict the aggressiveness of PCA which could help patients diagnosed with localised PCA avoid serious side effects by not undertaking unnecessary treatment.
Further reading and resources
Find out more about prostate cancer
Find out more about the treatments available for prostate cancer
Journal paper: Hamdy et al (2016) 10 year outcomes after monitoring, surgery, or radiotherapy for localised prostate cancer (the ProtecT trial)
Journal paper: Hackshaw-McGeagh et al (2016) Prostate cancer – evidence of exercise and nutrition trial (PrEvENT): study protocol for a randomised controlled feasibility trial.