Screening for prostate cancer: when is it a good idea?

By Prof David Servan-Schreiber

An editorial in the Journal of the National Cancer Institute has cast serious doubt on the usefulness of screening for prostate cancer. But such screening still has an important role if it meant to mobilize
the body’s natural anticancer defenses.

In a powerful editorial [1], Dr. Otis Brawley of the department of Epidemiology of Emory University in Atlanta, Georgia, sums up the situation and asks “does screening for prostate cancer save lives?” He observes that a large prospective study (a study that follows people in good health before they fall ill) in the United States found no benefit from such screening after more than ten years of follow-up. [2] Moreover, a European study had mixed results: for every man who avoided death from prostate cancer thanks to screening, 48 others received treatment even though they may not ever have actually required it. For many, these treatments led to complications that included repeated infections, and, if surgery was performed, a very high risk of erectile dysfunction. [3]

Clearly the sooner cancer is detected, the easier it is to cure it once and for all. This is the case for pre-cancerous colon polyps (screened by colonoscopy after the age of 50); for in-situ breast cancers (screened by mammography after the age of 50); or for early stages of cervical cancer (with Pap smears).

The complication for prostate cancer arises because the disease is usually very slow to develop. A large number of men have perfectly normal lives despite having prostate “micro-tumors” that may never develop into dangerous cancers. On the other hand, the treatments available for prostate cancer have major consequences on patients’ quality of life. Hence Dr. Brawley’s suggestion that we adopt a more skeptical attitude towards screening. He feels screening should only take place in very specific situations where the risk of aggressive cancer is particularly high. Which is not the case for most.

Personally, I think an essential dimension is missing from this debate. No-one has brought up the fact that lifestyle choices have a considerable influence on how a small, localized prostate cancer will evolve.

- Autopsies demonstrate that Japanese men aged 50 or more who die in car accidents have just as many “micro-tumors” of the prostate as North-American men or Europeans. And yet mortality from prostate cancer in Japan is seven times lower than it is in Western countries [4]. Yet when Japanese men move to the West, they develop aggressive prostate cancers at the same rate as Westerners. This means that as long as they live in Japan, their lifestyle prevents these micro-tumors from developing.

- Several studies have shown that life-style changes act on the biology of prostate cancer. At the University of California, San Francisco, Dr. Dean Ornish studied men with prostate cancer who were under “watchful waiting” following biopsies that confirmed the presence of cancerous tumors. The more these men were involved in a program to improve their life-style and habits (anti-cancer nutrition, physical activity, stress-management and emotional expression), the more their blood became capable of destroying the cancerous cells. In this small-scale study, none of the men who followed the program required other, more conventional forms of treatment; in contrast, several men in the “watchful waiting” control group did require surgery or radiotherapy. Moreover, Ornish demonstrated that life-style changes had an impact at the deepest level of the genes of prostate cells, by modifying their expression, and that these changes also activated the famous telomerase enzyme that protects chromosomes from premature aging. [5-7]

- Another study at Duke University noted that men with prostate tumors scheduled for surgery who consumed three soup-spoons of ground flaxseeds at breakfast every morning for a month experienced major reductions in their proliferation of cancerous cells as documented following the surgery. [8]

- Similarly, a study at the University of California, Los Angeles showed that men with initially high PSA levels (between 0.2 et 5 ng/ml) who drank a large glass (240 ml, or 8 ounces) of pomegranate juice every morning experienced far slower growth of their cancer (it took 54 months to double their PSA levels, compared to 15 months for men who did not drink pomegranate juice). [9]

- A Japanese study indicated that men who drank at least five small cups of green tea daily halved their risk of developing aggressive prostate cancer. [10]

- At the same university, researchers noted that men who ate the largest quantities of vegetables rich in carotenoids (strongly colored, red and orange vegetables) had up to 83% fewer prostate cancers than those who ate few of such vegetables, or none at all. [11]

- A large-scale Harvard study that has been following more than 40,000 male health professionals (doctors and others) since the 1980s has found that the simple consumption of tomato sauce twice a week reduced by 35% their probability of developing forms of cancer that spread beyond the prostate — the most dangerous type. (The tomatoes must be cooked in oil, to free as much lycopene as possible; lycopene has a beneficial effect on prostate cancer). [12] Men who already had prostate cancer and who consumed tomato sauce twice a week reduced the risk of their cancer progressing by 44%. [13]

- The omega-3s in oily fish (not only the omega-3s in ground flaxseeds) have a considerable protective effect for men who are genetically predisposed to aggressive prostate cancer. In a Swedish study at the Karolinska Institute, men who carried the high-risk genes, but who ate oily fish (such as salmon, sardines and mackerel) twice a week, reduced their likelihood of developing cancer to the level of men with normal genes [14].

- A study at Harvard noted that every 35 g (1.25 ounce) reduction in consumption of dairy products per day was associated with a 30% reduction in the risk of developing prostate cancer. [15]

- Another study by the same group at Harvard demonstrated that sustained physical exercise (3 to 4 hours per week of “fast walking” or equivalent) was associated with 70% less risk of developing prostate cancer. [16]

- In a Toronto hospital, impressive results were obtained by administering 2,000 IU of vitamin D3 daily to patients who had already been treated for prostate cancer, but whose PSA was once again on the rise. In this small sample of 14 patients, 9 saw their PSA stop growing — or even diminish — and overall the time it took for PSA to double rose from an average of 14 months to an average 25 months once vitamin D3 was started. This is a remarkable result for a vitamin that has no side effects, and which the Canadian Cancer Society has recommended for all older people during winter month (when the skin does not manufacture it as much for lack of sunshine). [17]

In other words, there’s a significant scientific argument for a new approach to prostate cancer screening. Yes, screening for prostate cancer can, paradoxically, be dangerous if it is associated with potentially very disabling treatments that are, as Dr. Brawley points out, often pointless. But screening is perfectly justified, and never dangerous, if it is used to motivate men to commit to anticancer lifestyle changes. Later, if those changes aren’t enough — if PSA levels don’t improve, for example — further medical intervention may be necessary and useful. But they many never be necessary.

BIBLIOGRAPHY

1. Brawley, O., Prostate Cancer Screening; Is This a Teachable Moment? Journal of the National Cancer Institute, 2009. 101: p. 1295-1297.
2. Plco_Project_Team, et al., Mortality results from a randomized prostate-cancer screening trial.[see comment]. New England Journal of Medicine, 2009. 360(13): p. 1310-9.
3. Erspc_Investigators, et al., Screening and prostate-cancer mortality in a randomized European study.[see comment]. New England Journal of Medicine, 2009. 360(13): p. 1320-8.
4. Yatani, R., et al., Trends in frequency of latent prostate carcinoma in Japan from 1965-1979 to 1982-1986. Journal of the National Cancer Institute, 1988. 80(9): p. 683-7.
5. Ornish, D., et al., Increased telomerase activity and comprehensive lifestyle changes: a pilot study. The Lancet Oncology, 2008: p. doi:10.1016/S1470-2045(08)70234-1.
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9. Pantuck, A.J., Phase-II Study of Pomegranate Juice for Men with Prostate Cancer and Increasing PSA, in American Urological Association Annual Meeting. 2005: San Antonio, TX
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