Diet and Lifestyle
Can patients' lifestyle influence the course of prostate cancer?
There is now emerging evidence to suggest ‘yes’ but probably not for everyone. Each patient and their stage, grade and biological pattern of their disease is unique. What works for one person may not work for another. The good thing is though, even if a healthy living programme does not help your cancer it will certainly help with many of the side effects of cancer treatments, help your body in other ways and empower you with a sense of self determination.
The latest NICE guidelines (2014) on prostate cancer now show the evidence for exercise after prostate cancer is strong enough to include it as a peer reviewed recommendation for oncology units throughout the UK. Every week major journals are publishing trials which highlight the benefits of lifestyle after cancer. The most important of these trials have been collected in a formal evidence review, commissioned by Macmillan Cancer Support led by Professor Robert Thomas, consultant Oncologist at Bedford and Addenbrooke’s Cambridge University Hospitals. He has also summarised the lessons learnt from these trials into evidence-based recommendations within his book Lifestyle and Cancer – The Facts, available via www.cancernet.co.uk.
Many trials evaluating exercise programmes have concluded that moderate activity can reduce fatigue, improve mood, psychological well being and body composition. Other trials have linked exercise, especially if combined with other lifestyle manoeuvres, with a reduced rate of PSA progression in active surveillance, and a reduced risk of relapse after radical treatments. There is insubstantial evidence, however, that fewer men gain benefit after radiotherapy.
Most of these trials indicate that 30 minutes a day or around 3-4 hours a week is the most beneficial, but any level of exercise is better than no exercise. Clearly, most of us do not get enough exercise. This should be a major lifestyle priority.
Exercise should be enjoyable if it is going to be sustained. Fortunately there are so many choices including gardening (the green gym), dancing, brisk walking, golf, running, cycling, swimming or formal exercise classes. You can search for exercise facilities in your area by postcode using a tool on www.cancernet.co.uk/exercise. You may also be able to ask your doctor for a referral to the local municipal gym on the National Exercise Referral Scheme for a 12-week supervised programme. If you are unfit, build up gradually; a fitter body will help you live longer and better.
Being overweight increases the risk of developing prostate cancer in the first place. There is also evidence that obese men present with more aggressive types (higher Gleason grades), increasing the complexity of treatments. This means they have to take hormone therapies for longer, increasing the risk of hot flushes and further weight gain. Obese men also have a higher risk of PSA relapse after radical treatments. A recent study from the USA has demonstrated an important link between lifestyle and genetics, which may explain why for some men obesity is bad and for others it has no effect. Overweight men with prostate cancer whose tumours were positive for the TMPRSS2:ERG genetic mutation had more than a 50% increased risk of dying from cancer after their diagnosis compared with normal-weight men.
There is an increasing emphasis on reducing calorie (energy) excess. Not only does this lead to obesity, but it produces changes in the blood stream, such as a rise in insulin-like growth factor (IGF), which cancers love. As well as total calorie intake, the type of food is important. Foods which are rapidly absorbed, such as processed sugar, refined wheat in bread and pasta are the worst culprits. Colourful fruits, berries and tomatoes have a lower risk of prostate cancer; flavanoid-rich foods such as beans, pulses, legumes show a lower risk of aggressive types of prostate cancer. Foods grilled at high temperature are known to be carcinogenic, and should be avoided.
Four foods in particular have been shown to work against the onset of prostate cancer in different ways: Pomegranate, rich in ellagic acid, has been shown to directly inhibit cell growth and can actually induce cell death in androgen sensitive and aggressive human prostate cancer cells. Green tea, rich in epigallocatechin gallate, blocks an enzyme which signals cells to proliferate faster, and metastasise. Broccoli, rich in isothiocyanate, has been found to inhibit prostate cancer cell growth; and curcumin, which gives turmeric its yellow colour, slows cancer cell growth by blocking the cell cycle, preventing the invasion and migration of cells.
Whole food supplements and the Pomi-T trial
These four foods have now been concentrated into a pill (Pomi-T). After an extensive and approved trial it is now commercially available. The trial was sponsored by Prostate Cancer UK, approved by the National Ethics Committee and the National Cancer Research Institute Committee (NCRI). Cancer survivors are attracted to the potential health benefits of a food supplement, with over 70% reporting regular intake. Pomi-T provides a wide spectrum of polyphenol nutrients whilst at the same time avoiding over-consumption of any one particular type. The trial showed a 63% reduction in PSA progression rate for those taking the pill against the control group who took a placebo. In addition, men on active surveillance taking the supplement have been shown to be less likely to opt for early invasive treatments.
Despite these findings Pomi-T is still classed as a food supplement, so can never become a recognised medicinal product or find its way into routine management. Further trials are hoping to look at the advantages of Pomi-T for men on hormone treatment, as well as for other cancers and conditions.
Another trial found that grapeseed extract was linked to a lower risk of prostate cancer after regular intake.
Minerals, vitamins and other chemical extracted foods
Vitamin E and selenium, once thought to be helpful have now been shown to have an increased prostate cancer incidence. High doses of zinc were also associated with an increased risk of prostate cancer in the study. The NCRI has stated that long-term vitamin and mineral consumption should be discouraged unless correcting a known deficiency. Saw palmetto and genistein have not shown any benefit for either prostate cancer or BHP. Likewise, the two most recent trials of lycopene extracts among men on active surveillance or watchful waiting found no difference in PSA progression, nor were there any links with the reduction in the risks of breast cancer with regular intake.
There is still a lot of research needed in this area, especially as there may be benefits for selected vitamin and mineral supplements in cases of known deficiencies; so it is important not to throw the baby out with the bathwater.
Most of us, for example, are deficient in Vitamin D3. Sunshine is the best source (up to half an hour per day is sufficient), so a moderate supplement in the winter months may be logical. Vitamin D can also be obtained from oily fish, whole grains, nuts, seeds and eggs.
Dairy versus non-dairy
Although there is no clear evidence that dairy products are harmful, it is now looking increasingly likely that there is a case for at least considering either complete avoidance, or reduced intake, of these.
The Chinese do not consume any dairy products, but if they start to adopt a western diet, the incidence of western diseases increases. It is believed that IGFs (Insulin-like Growth Factors) in dairy products are a possible cause. Significant evidence, however, is still lacking. Nevertheless many prostate patients keep off dairy (including cheese, yoghurts etc.), switching to alternatives based on soya, oats, rice and almond. If not, consider changing to organic dairy products.
PSA doubling time
PSA doubling time remains the most sensitive measure of response to a lifestyle initiative. To aid its calculation an app, PSACalc, has been developed and is currently available for the iPhone and iPad.
We hope that the guidance given in this section will encourage you to take positive action to improve your cancer journey.
Eat healthily keep fit, enjoy life: You are likely to live longer!
PCaSO is grateful to Professor Robert Thomas for contributing much of this article. For a full account of the trials and supporting evidence for this information, please see his article printed as a supplement to PCaSO Newsletter 46 (February 2014) which can be viewed here.