Prostate cancer primary prevention

Vitamins and medication
Evidence from epidemiological studies supports protective roles in reducing prostate cancer for dietary selenium, vitamin E, lycopene, and soy foods. High plasma levels of Vitamin D may also have a protective effect. Estrogens from fermented soybeans and other plant sources (called phytoestrogens) may also help prevent prostate cancer. The selective estrogen receptor modulator drug toremifene has shown promise in early trials. Two medications which block the conversion of testosterone to dihydrotestosterone, finasteride and dutasteride, have also shown some promise. The use of these medications for primary prevention is still in the testing phase, and they are not widely used for this purpose. The initial problem with these medications is that they may preferentially block the development of lower-grade prostate tumors, leading to a relatively greater chance of higher grade cancers, and negating any overall survival improvement. More recent research found that finasteride did not increase the percentage of higher grade cancers.

A 2008 study update found that finasteride reduces the incidence of prostate cancer by 30%. In the original study it turns that that the smaller prostate caused by finasteride means that a doctor is more likely to hit upon cancer nests and more likely to find aggressive-looking cells. Most of the men in the study who had cancer — aggressive or not — chose to be treated and many had their prostates removed. A pathologist then carefully examined every one of those 500 prostates and compared the kinds of cancers found at surgery to those initially diagnosed at biopsy. Finasteride did not increase the risk of High-Grade prostate cancer.

Green tea may be protective (due to its polyphenol content), although the most comprehensive clinical study indicates that it has no protective effect. A 2006 study of green tea derivatives demonstrated promising prostate cancer prevention in patients at high risk for the disease. Recent research published in the Journal of the National Cancer Institute suggests that taking multivitamins more than seven times a week can increase the risks of contracting the disease. This research was unable to highlight the exact vitamins responsible for this increase (almost double), although they suggest that vitamin A, vitamin E and beta-carotene may lie at its heart. It is advised that those taking multivitamins never exceed the stated daily dose on the label. Scientists recommend a healthy, well balanced diet rich in fiber, and to reduce intake of meat.

A 2007 study published in the Journal of the National Cancer Institute found that men eating cauliflower, broccoli, or one of the other cruciferous vegetables, more than once a week were 40% less likely to develop prostate cancer than men who rarely ate those vegetables. The phytochemicals indole-3-carbinol and diindolylmethane, found in cruciferous vegetables, has antiandrogenic and immune modulating properties.

Ejaculation frequency
In 2003, an Australian research team led by Graham Giles of The Cancer Council Australia concluded that frequent masturbation by males appears to help prevent the development of prostate cancer. Australian research concluded that the more men ejaculate between the ages of 20 and 50, the less likely they are to develop prostate cancer. The protective effect is greatest while men are in their twenties: those who had ejaculated more than five times per week in their twenties, for instance, were one-third less likely to develop aggressive prostate cancer later in life. The results contradict those of previous studies, which have suggested that having had many sexual partners, or a high frequency of sexual activity, increases the risk of prostate cancer by up to 40 percent. The key difference is that these earlier studies defined sexual activity as sexual intercourse, whereas this study focused on the number of ejaculations, whether or not intercourse was involved. Another study completed in 2004 reported that "Most categories of ejaculation frequency were unrelated to risk of prostate cancer. However, high ejaculation frequency was related to decreased risk of total prostate cancer." The report abstract concluded, "Our results suggest that ejaculation frequency is not related to increased risk of prostate cancer."

More fish oil, less vegetable oil
A high consumption of omega-6 polyunsaturated fatty acids (PUFAs), which are found in most types of vegetable oil (e.g. corn oil - the most consumed oil in USA, soybean oil, sunflower oil, etc.), increased prostate tumor growth, speeded up histopathological progression, and decreased survival, while the omega-3 fatty acids (e.g. in fish oil) had the opposite, beneficial effect.

Myristic and palmitic saturated fatty acids
Some researches have indicated that some specific saturated fatty acids (myristic acid and palmitic acid  are associated with increased risk of prostate cancer in a dose-dependent manner. Another study further investigated these and other saturated fatty acids. However it's still uncertain if this association is a cause or consequence of the disease.