19 November 2014
Men who are overweight or obese are at greater risk of developing advanced prostate cancers, including aggressive cancers that are fatal, a leading cancer prevention charity has found.
The finding was made after an analysis of the global scientific research into lifestyle factors and prostate cancer in the World Cancer Research Fund’s Continuous Update Project (CUP). The report, the most in-depth review to date, analysed 104 studies involving more than 9.8 million men and over 191,000 cases of prostate cancer.
A clearer picture has emerged, showing there is now strong evidence of a link between being overweight or obese and advanced prostate cancer. Annually we estimate that around 10% of advanced prostate cancer cases in the UK could be prevented, if men kept a healthy weight.
However, a less consistent picture has emerged of the links between prostate cancer risk and certain foods. The evidence linking diets high in calcium to an increased risk of prostate cancer has been downgraded from “strong” to “limited”. And evidence that foods containing lycopene (such as tomatoes) decrease the risk of prostate cancer, has been downgraded from “strong” to no conclusion possible. The evidence that a diet higher in dairy products increases risk, remains limited.
Our conclusions have changed as a result of studies into different prostate cancer types that have emerged since our previous detailed review of prostate cancer research in 2007. Today’s CUP report, the result of a partnership with Imperial College London, is the most in-depth review to date of research linking diet, physical activity, and weight to the risk of developing prostate cancer.
The evidence paints a complex picture in which not all prostate cancers are alike. More studies are separating out fatal, advanced or aggressive and non-advanced cancers. While this has clarified what we know about prostate cancer and body fatness, it has clouded our understanding of the relationship between prostate cancer and certain foods. We are not saying there is no link. What we are saying is, if there is a link, it is more difficult to see.
Kate Allen, Executive Director Science and Public Affairs at World Cancer Research Fund International, said: “The report’s finding in relation to being overweight or obese is important. It is the first time we have been able to show any kind of link between advanced prostate cancer and weight. It adds to our general understanding of the impact of being overweight or obese on cancer risk and helps inform our cancer prevention efforts.
“But the CUP also points to a more complicated picture than first thought. More research has emerged into lifestyle, diet and prostate cancer since our last review. The result is that some of the evidence linking certain foods to prostate cancer risk has become less clear.”
The emergence of a link between body fatness and advanced prostate cancer could have important implications. It may raise questions in relation to prostate cancer screening, in particular, whether excess weight ought to be included alongside factors like family history in discussions between GPs and men at risk of advanced prostate cancer.
Dr Jonathan Rees, GP and Chair of the Primary Care Urology Society, said: “With so much controversy over the merits of screening for prostate cancer, it is vital in primary care for us to understand which patients are most at risk of developing this disease and are therefore most likely to benefit from PSA testing. The findings of this review have significant implications: they add strength to the rationale for encouragement of a healthy lifestyle and control of weight, in terms of cancer prevention; they point us towards recognising overweight or obesity as a risk factor to take into account when discussing screening with patients; and they point us towards avenues of research that may help us to reduce the impact of this disease which kills over 10,000 men a year in the UK alone.”
We recommend men maintain a healthy weight and check their BMI and waist measurement regularly. We also recommend following our Cancer Prevention Recommendations to reduce the risk of prostate cancer as well as other cancers and chronic diseases.