Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. It occurs when cells of the prostate mutate and begin to multiply out of control. These cells may spread (metastasize) from the prostate to other parts of the body, especially the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, erectile dysfunction and other symptoms.

Prevalence Rates
Rates of prostate cancer vary widely across the world. Although the rates vary widely between countries, it is least common in South and East Asia, more common in Europe, and most common in the United States. According to the American Cancer Society, prostate cancer is least common among Asian men and most common among black men, with figures for white men in-between. However, these high rates may be affected by increasing rates of detection.

Risk Factors
Many factors, including genetics and diet, have been implicated in the development of prostate cancer. Prostate cancer develops most frequently in men over fifty. This cancer can occur only in men, as the prostate is exclusively of the male reproductive tract. It is the most common type of cancer in men in the United States, where it is responsible for more male deaths than any other cancer, except lung cancer.

Symptoms
Early prostate cancer usually causes no symptoms.  Many men who develop prostate cancer never have symptoms, undergo no therapy, and eventually die of other causes. Often it is diagnosed during the workup for an elevated PSA noticed during a routine checkup.

Sometimes, however, prostate cancer does cause symptoms, often similar to those of diseases such as benign prostatic hypertrophy. These symptoms may include:

• difficulty starting and maintaining a steady stream of urine,
• frequent urination,
• increased urination at night,
• blood in the urine and
• painful urination.

Prostate cancer is associated with urinary disfunction as the prostate gland surrounds the prostatic urethra. Changes within the gland therefore directly affect urinary function.

Advanced prostate cancer can spread to other parts of the body and this may cause additional symptoms. The most common symptom being bone pain, often in vertebrae (bones of the spine), pelvis or ribs. Spread of cancer into other bones such as the femur is usually to the proximal part of the bone. Prostate cancer in the spine can also compress the spinal cord, causing leg weakness and urinary and fecal incontinence. 

Sexual Dysfunction
Prostate cancer may also cause problems with sexual function, such as difficulty achieving erection or painful ejaculation.The Vas deferens deposits seminal fluid into the prostatic urethra and secretions from the prostate gland itself are included in semen  content, which is why Prostate Cancer can affect sexual performance and cause painful ejaculation.

Diagnosis
Prostate cancer is most often discovered by physical examination or by screening blood tests, such as the PSA (prostate specific antigen) test. There is some current concern about the accuracy of the PSA test and its usefulness. Suspected prostate cancer is typically confirmed by removing a piece of the prostate (biopsy) and examining it under a microscope. Further tests, such as X-rays and bone scans, may be performed to determine whether prostate cancer has spread.

Treatment
Prostate cancer can be treated with:

• surgery,
• radiation therapy,
• hormonal therapy,
• occasionally chemotherapy, proton therapy, or some combination of these.

Drugs
There are currently no pharmaceutical drugs that have been proven effective in preventing prostate cancer. Finasteride (Proscar) showed some promise in reducing overall cancer incidence but was, unfortunately, associated with a significant increase in advanced cancers. Finasteride is therefore no longer considered suitable for prostate cancer prevention.

Two natural agents, selenium and vitamin E, have been found effective in prostate cancer prevention. The Nutritional Prevention of Cancer (NPC) study concluded that supplementing with 200 micrograms/day of elemental selenium (in the form of high-selenium yeast) reduced prostate cancer risk by 63%. The large Finnish ATBC study concluded that supplementing with 50 mg/day (50 IU/day) of synthetic alpha-tocopheryl-acetate reduced prostate cancer risk and mortality by 32% and 41% respectively. 

Based on these and other findings, the National Cancer Institute has embarked upon a major trial, the Selenium and Vitamin E Cancer Prevention Trial (SELECT). The trial, opened for recruitment in July 2001, now has a total enrollment of 35,534 men with a median age of 62 years (range of 50-93 years) who were free of prostate cancer. The expected follow-up time is 7-12 years. After much deliberation and a thorough review of the literature, the SELECT Steering Committee decided that the supplements to be evaluated would be 200 micrograms/day of elemental selenium in the form of L-selenomethionine and 400 IU/day of synthetic alpha-tocopheryl acetate. The trial design will involve 5 pair-wise comparisons of prostate cancer incidence, in association with – vitamin E vs placebo, selenium vs placebo, vitamin E plus selenium (combination) vs placebo, combination vs vitamin E, and combination vs selenium. The Steering Committee points out that there is strong evidence that 200 micrograms/day of elemental selenium is entirely safe, as is up to 1000 mg/day of vitamin E. They acknowledge that natural alpha-tocopherol is significantly more effective than synthetic alpha-tocopheryl acetate and that gamma-tocopherol may be even more effective than either as far as prostate cancer prevention is concerned. However, due to the fact that more clinical trial data is available on synthetic alpha-tocopheryl acetate they decided to go ahead with this form. All study participants will also receive a daily multivitamin devoid of selenium and vitamin E, but including 400 IU of vitamin D3.
Lippman, SM, et al. Designing the Selenium and Vitamin E Cancer Prevention Trial (SELECT). Journal of the National Cancer Institute, Vol. 97, January 19, 2005, pp. 94-102

There is growing evidence that certain micronutrients, more specifically antioxidants, may help prevent some forms of cancer. Selenium, for example, has been found highly effective in preventing prostate cancer. Researchers at the Johns Hopkins School of Public Health now report that gamma-tocopherol, the form of vitamin-E found in most foods, is also effective in preventing prostate cancer. Their study involved over 20,000 male residents of Washington County, Maryland who had donated blood in 1974 and 1989. A total of 324 men had developed prostate cancer by 1996. These men were each matched with two healthy controls in regard to age, race, and date of blood donation. Comparing the blood levels of micronutrients in cases and controls found no significant differences in concentrations of alpha-carotene, beta-carotene, total carotene, beta-cryptoxanthin, lutein, lycopene, retinol, and ascorbic acid (vitamin-C). There was, however, a difference in gamma-tocopherol levels between cases and controls with controls having significantly lower levels. For the men who donated blood in 1989 it was observed that men with the highest gamma-tocopherol levels had an almost 5 times lower incidence of prostate cancer than did those with the lowest levels. There was also some evidence that higher circulating levels of retinyl palmitate (formed from vitamin-A and stored in the liver) were protective against prostate cancer. The researchers conclude that gamma-tocopherol may help protect against prostate cancer, but note that lycopene did not appear to have any protective effect.Huang, Han-Yao, et al. Prospective study of antioxidant micronutrients in the blood and the risk of developing prostate cancer. American Journal of Epidemiology, Vol. 157, February 15, 2003, pp. 335- 44

At least five major clinical trials have concluded that higher levels of selenium (in blood or toenail clippings) are associated with a sharply reduced risk of prostate cancer. The Nutritional Prevention of Cancer (NPC) trial found that supplementing with 200 micrograms/day of selenium cuts prostate cancer risk in half. Researchers at the Harvard Medical School now weigh in with another study confirming the beneficial effects of selenium. Their study involved 22,000 healthy, male physicians who were enrolled in the study in 1982 and had blood samples taken at that time. Sufficient samples to analyze for selenium content and PSA level were available for 586 men diagnosed with prostate cancer as well as for 577 controls matched for age and smoking status.

After 13 years of follow-up the researchers concluded that study participants with a plasma selenium level of 0.12-0.19 ppm had a 50% lower incidence of advanced prostate cancer than did men with a level of 0.06-0.09 ppm. The correlation was only apparent in men with a PSA level of more than 4 ng/mL and was particularly strong for those with a baseline (1982) PSA level greater than 10 ng/mL. For these men a high selenium level corresponded to a 70% decrease in the risk of advanced prostate cancer. The researchers also observed a trend for a lower incidence of localized prostate cancer with high selenium levels, but this trend was not statistically significant. They conclude that selenium is perhaps not too effective in preventing the initiation of prostate cancer, but that it is highly effective in slowing down tumor progression. They believe that selenium acts by selectively killing off cells whose DNA has been extensively damaged, by inhibiting cellular proliferation, and by its role as a key component of glutathione peroxidase, which protects cells from peroxide damage.
Li, H, et al. A prospective study of plasma selenium levels and prostate cancer risk. Journal of the National Cancer Institute, Vol. 96, May 5, 2004, pp. 696-703
Taylor, PR, et al. Science peels the onion of selenium effects on prostate carcinogenesis. Journal of the National Cancer Institute, Vol. 96, May 5, 2004, pp. 645-47 (editorial) 

So far, research does not support definite nutritional guidelines for preventing prostate cancer. However, you can reasonably act on these suggestions:

• Choose a Mediterranean Diet.  Several studies have found a clear association between the western lifestyle and an increased risk of prostate cancer. A high intake of fat, meat and dairy products has been found to be particularly detrimental.
  
• Avoid high-fat foods. Prostate cancer rates vary greatly from one country to another, with the highest rates appearing in countries where people tend to eat a lot of fat. A diet high in saturated fats (such as animal fats found in red meat) may pose the greatest risk.
• Make healthy choices. Choose whole-grain foods, such as brown rice and whole-wheat bread. Limit sweets and salt.Consuming fried or charcoal-grilled red meat has been clearly associated with increased risk. A high intake of alpha-linolenic acid and calcium from dairy products has both been associated with higher risk. A Swedish study found that men who consumed 600 mg/day of calcium from dairy products had a 32% greater risk than those consuming 150 mg/day or less.
• Drink alcohol in moderation. Generally, this means no more than two drinks a day for men.
• Eat a variety of fruits and vegetables. A diet high in fruits and vegetables has been linked to a lower risk of various kinds of cancer. Recent studies cast doubt on the theory that lycopene — an antioxidant found in tomatoes — lowers prostate cancer risk. But don't stop eating tomatoes. Eating plenty of all kinds of vegetables, including tomatoes, may help ward off prostate cancer and other cancers.
• Eat foods rich in omega-3 fatty acids. While a diet high in most kinds of fat is linked to a higher risk of cancer and other health problems, there is an exception. Omega-3 fatty acids — a type of fat found in cold-water fish such as salmon, herring and mackerel — appear to reduce the risk of certain cancers. Several studies have shown an inverse relationship between blood levels of fish oils (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) and the risk of prostate cancer. A study just completed by medical researchers at the Karolinska Institute confirms this association.  The Swedish study involved 3136 pairs of male twins born between 1886 and 1925. The participants completed food frequency questionnaires in 1961 and 1967 and were then followed up for 30 years. By December 31, 1997 the researchers had recorded 466 diagnoses of prostate cancer (340 fatal ones). The average age of diagnosis was 76.7 years. After adjusting for other known risk factors the researchers conclude that men who never eat fish have a two- to three-fold higher risk of prostate cancer than do men who eat moderate to high amounts. The researchers emphasize that only fatty fish such as salmon, herring and mackerel, which contain high amounts of omega-3 fatty acids (EPA and DHA), would be expected to be beneficial.Terry, Paul, et al. Fatty fish consumption and risk of prostate cancer. The Lancet, Vol. 357, June 2, 2001, pp. 1764-66 (research letter)

Experts are still studying other foods to see whether they help prevent prostate cancer. While the verdict's still out, eating more of these foods probably won't hurt — and may help prevent cancer and other health problems:

• Eat soy products and legumes. Soybeans and other legumes contain phytoestrogens, which are plant-based chemicals that behave like the hormone estrogen in the human body. These chemicals might help to prevent prostate cancer. In fact, one possible explanation for lower rates of prostate cancer in Asian men is that they eat more soy protein.
• Drink green tea. Green tea contains antioxidants such as polyphenols that may help prevent certain cancers and other health problems. 

Prognosis
The age and underlying health of the man as well as the extent of spread, appearance under the microscope, and response of the cancer to initial treatment are important in determining the outcome of the disease. Since prostate cancer is a disease of older men, many will die of other causes before a slowly advancing prostate cancer can spread or cause symptoms.