Prostate cancer: A killer among us

Prostate cancer is on the increase. Every year, more than 21,000 men are diagnosed with it and approximately 10,000 will die. And last week it was announced that prostate cancer is now set to overtake lung cancer as the most common cancer in men in the next three years. The statistics are chastening for any man, but the news is not all bad.

The vast majority of cases affect the elderly (95 per cent of cases occur in men over the age of 60), and it is often said of the illness that more men die with it than of it.

Unlike lung cancer, prostate cancer is largely treatable. In addition to this, there is growing evidence to suggest that there is plenty that men can do to help to reduce their chances of getting prostate cancer in the first place.

“There is strong evidence of a link between diet and development of cancers, particularly breast and prostate cancer,” says Professor Jonathan Waxman, the chairman of the Prostate Cancer Charity and professor of oncology at Imperial College, London. “When people talk about this matter the word ‘crank’ comes up, but some of the best evidence comes from some huge studies.”

It has been found that people in countries such as China and Japan are far less likely than Westerners to develop prostate cancer. Notably, when people migrate to the US, their rates of prostate cancer rise greatly and, since their genetic make-up is the same, there appears to be something about living in America that increases these men’s chances of developing cancer. Diet is the number one suspect.

There is a strong link between low risk of prostate cancer and a vegetarian diet, and the most protective diet includes yellow beans, such as soya, says Professor Waxman. Vegetarians are approximately half as likely to develop prostate cancer as meat-eaters. And while some foods appear to reduce the risk of prostate cancer, others seem to have the opposite effect. A study from Holland showed a significant link between diets high in cured meats and dairy products and a high risk of developing prostate cancer.

Soya beans are widely known for their possible anti-cancer potential, and the latest discoveries are encouraging. It has been found that the beans, which contain compounds called isoflavanoids, can actually inhibit prostate cancer cell growth in the laboratory.

Soya protein can be found in many foods such as tofu, soya milk and yoghurt. The Eastern diet is based around soya proteins as an alternative to meat. In one study, Japanese men in Hawaii who consumed tofu approximately once per day, were 65 per cent less likely to develop prostate cancer in comparison with men eating tofu less than once a week.

Numerous studies have shown associations of higher dietary fruit and vegetable intake with lower risks of a whole range of cancers. But it’s the tomato that has been of particular interest recently in connection to its role in the prevention of prostate cancer.

Tomatoes contain not only vitamin C and E, but also an antioxidant called lycopene, which is the compound that gives the fruit its red colour. Cooked tomatoes have a stronger lycopene content than raw ones, and that means even tomato ketchup can be of benefit. Results from a six-year study of 48,000 men found that men who ate the most processed tomatoes, such as found on pizza toppings and tomato ketchup, were far less likely to develop prostate cancer. In one US study, a high intake of tomatoes and tomato products was shown to reduce the total risk of prostate cancer by 35 per cent.

These days even Heinz states a lycopene content on bottles of its tomato ketchup. The last New York mayor, Rudolph Giuliani, has also declared that he now eats large amounts of plum tomatoes, having been diagnosed with prostate cancer.

Another antioxidant is selenium, which can protect against free-radical damage. One of the richest sources of selenium is brazil nuts. Selenium is also found in sunflower seeds, wholewheat bread, avocados and lentils and has been shown to reduce the incidence of prostate cancer. A study in the journal of The National Cancer Institute in 1988 found that men with the highest level of selenium had one-third the risk of developing prostate cancer compared with men with the lowest selenium levels. Selenium levels in soil have fallen sharply in recent decades and this is one mineral that is difficult to obtain in a normal diet. There is a case for taking a daily supplement.

Other dietary factors that may help reduce the risk of prostate cancer include antioxidants, like vitamin C, which is found naturally in many vegetables. Others include vitamin E (found in spinach, apples and seeds) and beta carotene (found in carrots). Broccoli may also play a role in the fight against cancer. It contains substantial qualities of isothyocyanates, which are also antioxidants.

In addition, men might do well to eat at least two or three portions of oily fish a week. Two studies in 1999 found that a high level of Omega-3 fatty acids in the body was associated with a reduced risk with prostate cancer. Oily fish such as salmon, trout, tuna, mackerel and herring are rich in healthy fats known as Omega-3 fatty acids. Given that any cancer gets about one in three of us, researchers from Minneapolis, found that eating whole grain foods (bread, rice, or pasta) four times a week reduces any cancer risk by 40 per cent.

No one wants to become neurotic about diet, but following a healthy diet can be pleasurable. The traditional Mediterranean diet has many of the right elements. So what should you do? Eat lots of tomatoes, fresh fruit and vegetables, whole grains and oily fish. Cut down on dairy products, consider taking a selenium supplement and avoid too much meat.

Provided by ArmMed Media
Revision date: July 4, 2011
Last revised: by Janet A. Staessen, MD, PhD