Preventing prostate cancer
A number of dietary and lifestyle changes can help you avoid this disease or at least slow its progression.The controversial PSA test-a blood test commonly used to screen for prostate cancer-is doing more harm than good, and should no longer be offered to healthy men, according to a US government advisory panel.
Rather than saving lives, this routine test-which looks for high levels of prostate-specific antigen (PSA) in the blood circulation-is contributing to the overdiagnosis of prostate cancer and unnecessary treatments that can have devastating life-long conse-quences, such as impotence and incontinence, the US Preventive Services Task Force (USPSTF) stated in its Recommendation Statement. European countries, including the UK, do not offer routine PSA screenings for these reasons.
Back in 2008, the USPSTF advised against routine PSA testing for men over the age of 75, but now they are recom-mending that all healthy men skip the test, regardless of age. This is because, based on the current evidence, the experts are forced to conclude that “the benefits of PSA-based screening for prostate cancer do not outweigh the harms” (Ann Intern Med, 2012 May 21; Epub ahead of print).
Harm vs benefit
The main goal of prostate cancer screening is to save lives. But after reviewing two major clinical trials on PSA testing published since 2008, the USPSTF discovered that the number of men who avoided death due to prostate cancer because of screening after 10 to 14 years was very small.
The first trial, conducted in the US, could find no reduction in prostate-cancer deaths as a result of screening, while the second trial-conducted in seven Euro-pean countries-showed that more than 1000 men have to be screened to prevent a single prostate-cancer death. Even in this trial, five of the seven countries reporting results did not find a statistically significant reduction in deaths.
On the other hand, there is strong evidence that PSA testing is associated with significant harm. Prostate cancer often grows so slowly that many men who have it detected during screening are likely to never need treatment. Yet, nearly 90 per cent of men with PSA-detected prostate cancer go on to have early treatment with surgery, radiation and/or hormone therapy-all of which can have disastrous consequences. Indeed, up to five out of 1000 men will die within one month of surgery, and at least 20 per cent and 30 per cent of men undergoing surgery and radiation therapy, respectively, will suffer serious long-term side-effects such as urinary incon-tinence, erectile dysfunction and/ or bowel dysfunction. Hormone therapy is also associated with erectile dysfunction, as well as breast enlargement and hot flashes.
What’s more, routine PSA testing results in high rates of false positives (indicating cancer when it’s not there) that lead to yet more tests, including tissue biopsy, which comes with its own risks, including haematospermia (blood in the semen) and urinary problems.
Despite this evidence, many doctors-as well as the patients themselves-are still clinging to the PSA test.
However, there are other ways to deal with prostate cancer. One of them is to work out how to keep the prostate healthy and prevent the disease naturally.
Natural prevention
Like many other cancers, prostate cancer appears to be heavily influenced by nutrition and lifestyle. Taking supplements, and paying attention to what you eat and your level of physical activity, could slash your risk of the disease and possibly slow its progression if you are diagnosed with it.
- Fill up on fish. Eating fatty fish, which contains high levels of omega-3 fatty acids, can protect against prostate cancer-possibly by combatting inflammation. In a study of more than 6000 Swedish men followed for 30 years,those who ate no fish whatsoever had a two- to threefold higher frequency of prostate cancer than those who atemoderate or high amounts of fish (Lancet, 2001; 357: 1764-6). In another trial, dietary omega-3 intake appeared to dramatically cut the risk of aggressive prostate cancer. Men eating fatty fish like salmon once or more each week had a more than 60-per-cent lower risk of having an advanced form of the disease (Clin Cancer Res, 2009; 15: 2559-66). Trials are currently underway to see whether omega-3 supple-ments can slow or even reverse the progression of prostate cancer. Preliminary evidence from a small, short-term trial suggests that supplementing with fish oil in conjunction with a low-fat diet can reduce the number of rapidly dividing cells in prostate-cancer tissue (Cancer Prev Res [Phila], 2011; 4: 2062-71).
- Up your tomato intake. The humble tomato seems to protect against prostate cancer, too. Harvard researchers found that men who ate lots of tomatoes and tomato products (such as tomato sauce and pizza) reduced their risk of prostate cancer by 35 per cent. As for aggressive forms of prostate cancer, high tomato intakes cut the risk by more than half (J Natl Cancer Inst, 1995; 87: 1767-76). Scientists suspect that lycopene, a potent antioxidant found in the fruit, is responsible for the anticancer effect. In fact, a Finnish study found a strong link between blood lycopene levels and overall cancer rates in men (Ann Epidemiol, 2009; 19: 512-8). Several studies have looked at the effects of lycopene supplementation in men with prostate cancer. According to one review of eight trials, the higher the lycopene intake, the lower the levels of PSA in the blood. It also reported that lycopene supplements can delay prostate-cancer progression as well as reduce symptoms such as pain and urinary tract problems (Prostate Cancer Prostatic Dis, 2009; 12: 325-32).
- Say yes to sprouts. Eating plenty of vegetables is known to cut the risk of cancer, and the cruciferous kindmay be especially helpful against prostate cancer. One study found that, compared with men eating less than one serving a week, those who consumed three or more servings of cruciferous vegetables per week, such as Brussels sprouts, broccoli and cauliflower, reduced their risk of prostate cancer by 40 per cent. Their high content of the carotenoids lutein and zeaxanthin, as well as their stimulatory effects on the breakdown of environmental carcinogens associated with prostate cancer, are thought to be behind these vegetables’ anticancer effects (J Natl Cancer Inst, 2000; 92: 61-8).
- Make it Mediterranean. The traditional Mediterranean diet appears to be protective against prostate cancer. Typically, such a diet includes high amounts of vegetarian foods such as cereals, vegetables, legumes (beans), and dried and fresh fruit; olive oil as the main fat source; low intakes of saturated animal fats, processed red meat anddairy products; regular consumption of small fish; and low alcohol intake (wine with meals). Men eating this type of food are significantly less likely to develop prostate cancer compared with those who have a typical Western diet (Actas Urol Esp, 2012; 36: 239-45).
- Go green with your tea. An Italian study of men with high-grade prostate intraepithelial neoplasia, an abnormality of prostatic tissue believed to precede the development of cancer, investigated the effects of taking 600 mg/day of green tea catechins (the active ingredient in the brew) or a placebo for one year. The results showed that prostate cancer developed in just over 3 per cent of the men given the green tea extract compared with 30 per cent of those given the placebo. This suggests that green tea may help to prevent prostate cancer in men at high risk of developing the disease (Cancer Res, 2006; 66: 1234-40).
- Supplement with selenium. In a trial of around 1300 Americans with a history of skin cancer, University of Arizona researchers looked at the impact of giving half of them 200 mcg of selenium daily and the other half a placebo. The participants took the pills for fo
ur and a half years, and were then followed for an additional two years. Although there was no reduction in the number of skin cancers that developed, there was a 37-per-cent reduction in total cancer incidence and a 50-per-cent reduction in cancer deaths in the selenium group vs the placebo group. Moreover, the risk of having prostate cancer in the selenium group was slashed by 63 per cent (JAMA, 1996; 276: 1957-63).
- Seek the sun. Calcitriol, the active form of vitamin D, is known to inhibit the prolifera-tion and invasiveness of prostate-cancer cells (ISRN Urol, 2011; 2011: 301490). And men with lower levels of vitamin D appear to be more likely to develop the disease (J Androl, 2002; 23: 9-17). Making sure to get enough vitamin D, whether from sun exposure or supplements, may therefore be another way to ward off prostate cancer. (See WDDTY vol 23 no 4 for more information on vitamin D and how to maintain optimal levels.)
- Stay active. Regular physical activity may have a protective effect against prostate cancer (World J Urol, 2012; 30: 167-79). It might also help to slow the disease progression and improve the chances of survival in men already diagnosed with the condition. When Harvard researchers observed 2705 men diagnosed with prostate cancer over a period of 18 years, they found that those who engaged in regular physical activity-particularly vigorous activities such as cycling, swimming, tennis and jogging-were significantly less likely to die from prostate cancer specifically or any other cause in general (J Clin Oncol, 2011; 29: 726-32).
Joanna Evans
