Prostate Cancer Canada Network

In The News

Well-Done Meat Consumption May Increase Prostate Cancer Risk
Research into the dietary habits of about a thousand men from the Cleveland area has found that a high consumption of meats, especially of red meat prepared by grilling, is positively associated with an increased risk of developing aggressive prostate cancer. This particular study, which was led by Dr. John Witte of the University of California, San Francisco (UCSF), has a number of limitations, but it does add support to other investigations connecting meat consumption with cancer risk.

Toronto researchers speculate regarding a link between prostate cancer and oral contraceptive use
Very preliminary and speculative research, designed to spark further inquires, suggests that there may be a connection between oral contraceptive use and rising rates of prostate cancer. One theory is that the widespread use of birth-control pills in various populations may result in a higher level of estrogen in the environment, which might, in turn, increase prostate cancer risk.

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Causes and Risk Factors

WHO IS AT RISK FOR DEVELOPING PROSTATE CANCER?

Any normal man can develop prostate cancer because normal men have male hormones. The prostate does not develop properly without testosterone, the most common male hormone, so men with severe male hormone deficiencies (or those who have been castrated before puberty) are not at risk.

There are four main risk factors: age, race, family history, and diet.

The risk of developing prostate cancer increases with age. It is very rare (although possible) to be diagnosed with prostate cancer before age 40, but a man’s risk increases quickly after age 50. More than 80 per cent of all prostate cancers are diagnosed in men over 65 years old and 90 per cent of men who die from the disease are in this age group.

The table below lists the risk for developing prostate cancer by age group:

Age group	Risk of prostate cancer
Under 50	0.219%
50 to 59	2.134%
60 to 69	6.710%
70 to 75	5.250%
Over 75	11.6%

Discuss your prostate cancer risk with your doctor when you turn 40. Most men should start having yearly digital rectal exams and PSA tests starting at age 50. Men in a high risk group (for example, if the disease runs in your family) should start getting tested earlier.

Race and Nationality
Research and statistics suggest that geographical, cultural, and racial factors affect men’s prostate cancer risk. Canadian men of African or Caribbean ancestry have the highest risk. Prostate Cancer Canada puts it bluntly: “African-American men are 65% more likely to develop prostate cancer than Caucasian-American men, and the risk of an African-American man dying of prostate cancer is about 100 times that of a Chinese man living in China.” The chart shows the racial groups at lowest to highest risk (from left to right).

Note: These racial categories are based on those most frequently used by cancer registry databases in the United States. These databases usually categorize South Asian people (defined as those from India, Pakistan, Bangladesh, and Sri Lanka) as part of the “Asians and Pacific Islanders” group. However, studies suggest that South Asian men are at a higher risk for prostate cancer than others within the “Asians and Pacific Islanders” category. As you can tell, racial and ethnic categories are difficult to determine and to describe accurately and sensitively; The Network has made every effort to be clear and respectful when discussing these issues.

Scientists are not sure why race appears to affect prostate cancer risk. There are subtle genetic and hormonal differences among the races that may predispose certain groups to prostate cancer. For example, levels of testosterone tend to vary.

Cultural and geographic factors also probably come into play. Diet, in particular, may play a role in the development of prostate risk. We think this because of studies looking at the prostate cancer risk of men from various racial and national backgrounds who have moved to North America. As these men start to adapt by eating different foods from those usually consumed in their countries of origin, their prostate cancer risk changes. For example, Asian men who remain in China or Japan are at lower risk than Chinese or Japanese men who have moved to North America.

Where you live also affects your prostate cancer risk because of environmental factors such as exposure to chemical carcinogens (e.g., insecticides), lead, or sunlight. Perhaps because of the benefits of vitamin D, prostate cancer risk is less for those who live close to the equator and get more hours of sunlight in a day. Human skin can produce vitamin D when it is exposed to the UVB (Ultraviolet medium waves) in sunlight, but UVB only reaches ground level when the sun is high in the sky. Those furthest from the equator, then, can go for months without the opportunity to produce vitamin D from sunlight. Perhaps this lack of exposure to sunlight is part of the reason that, in national comparisons, the highest incidence of prostate cancer is in Scandinavian countries. Another interesting fact is that dark skin absorbs less sunlight than light skin, which may contribute to the higher incidence of prostate cancer among men of African or Caribbean ancestry.

Family History
If one of your first-degree relatives (your father or brother) has had prostate cancer you are approximately 2 to 2 1/2 times more likely than the average man to be diagnosed with the disease during your lifetime. Having two first-degree relatives with prostate cancer increases your risk to about 5 to 10 times that of a man with no family history, and your risk soars to almost 100% if three or more first-degree relatives have had prostate cancer. If you find yourself in this last category, remember the phrase “in your lifetime” and remember that statistics are not destiny. Nevertheless, if a close relative has been diagnosed with prostate cancer, tell your doctor, get regular checkups, and take preventative measures. If more distant relatives have had prostate cancer, uncles and cousins, for example, you should still be extra careful. However, the closer the relative with prostate cancer (and the more close relatives who have been diagnosed), the greater your risk.

Estimates are that approximately 10 per cent of all the prostate cancer cases are hereditary, in other words, that they are a consequence of an inherited genetic predisposition. Research is preliminary, but the genes HPC1, HPC2, HPCX, and CAPB seem to be responsible for an increased likelihood of developing prostate cancer, although other genes are involved too. To date, no genetic tests are available for routine screening because this research is so new.

The risk of prostate cancer also appears to increase in men with BRCA1 and BRCA2 gene mutations; these are commonly associated with hereditary breast and ovarian cancer. Men with BRCA1 mutations have a slightly increased risk. Men with BRCA2 mutations have an estimated lifetime risk of almost 20 per cent. There is a simple blood test to see whether you have BRCA1 or BRCA2 mutations, so, if your mother or sisters have had breast or ovarian cancer, you may wish to have this test.

Alert: Men with a family history of prostate cancer or with BRCA1 or BRCA2 mutations should begin annual prostate cancer screening by age 40. Experts estimate that 65 per cent of the men who are diagnosed with prostate cancer before the age of 56 have hereditary prostate cancer.

Diet
Research suggests that diets high in saturated fat and low in fibre and in fruits and vegetables are associated with higher prostate cancer risk. Also, phytoestrogens, selenium, lycopene, garlic, vitamin C, and vitamin D seem to play a role in reducing prostate cancer risk. (See the information on the role of diet in prostate cancer prevention.)