Prostate Cancer

Prevention

Much effort has been devoted to a search for environmental factors that might serve as promoters for prostate cancer. The incidence of microscopic prostate cancer is similar among men in the United States and in all the other counties that have been examined. But the mortality rates from prostate cancer differ from one country to another and even within different regions of the United States. These differences suggest that some environmental factor or factors influence the progression of prostate cancer from microscopic tumors to clinically significant ones. Two possible factors are diet and sunlight exposure. Binge drinking may also play a role. And one medication has been hypothesized to reduce the risk of prostate cancer, though research suggests it may actually boost the chances of developing the more severe kind.

This section includes further information on prostate cancer and:

• Diet
• Sunlight exposure
• Weight
• Binge drinking
• Finasteride

Diet

The majority of studies on the relationship between dietary fat and prostate cancer have found that a higher fat intake is associated with an increased risk of prostate cancer. Fat makes up 30 percent to 40 percent of the calories in the American diet, compared with 15 percent in Japan. These differences in fat intake may help explain the much lower death rate from prostate cancer in Japan, as well as the great variability in mortality rates around the world. Another possibility is that people who eat a high-fat diet are less likely to eat healthful foods, such as vegetables.

A high intake of vegetables may lower the risk of prostate cancer. According to a study of 628 men with prostate cancer published in 2000, men who ate 28 or more servings of vegetables a week had a 35 percent lower risk of prostate cancer than those who ate 14 or fewer servings per week. Cruciferous vegetables, such as cabbage and broccoli, appeared to provide a further protective effect. Moderate evidence suggests that other dietary components, including lycopene (an antioxidant found in tomatoes and tomato-based products), selenium (a trace element), and vitamin E may also reduce risk.

Calorie intake may also affect prostate cancer risk. A 2003 study found that men who ate the most calories (around 2,600 per day) were nearly four times as likely to have prostate cancer as men who ate the least calories (1,100 per day). However, previous studies on the link between prostate cancer and high-calorie diets have produced inconclusive results, so more research on this topic is needed before recommendations on calorie intake can be made.

Sunlight exposure

According to one study, sunlight may protect against prostate cancer by promoting the body's production of vitamin D. Vitamin D is synthesized in the skin during exposure to the ultraviolet (UV) radiation in sunlight. When the incidence of prostate cancer mortality was examined in white men in 3,073 counties in the United States, areas with the lowest amount of UV radiation had the highest mortality rates. Overall, deaths from prostate cancer were highest in the Northeast and lowest in the Southwest.

In addition, a laboratory study found that physiological concentrations of the active form of vitamin D change the makeup of prostate cancer cells so that they are less likely to spread. Further studies are needed to determine whether vitamin D supplements can prevent or treat prostate cancer. Spending at least half an hour in the sunlight each day and drinking fortified milk are the best ways to get vitamin D; megadose supplements can be toxic. For those who take supplements, the recommended dosage of vitamin D is 400 to 800 IU daily.

Weight

Obesity (having a body mass index [BMI—an expression of weight and height—of 30 or more) is known to increase the risk of cancer as well as its severity. A 2003 study found that men who were obese were 20 percent more likely to die of prostate cancer than normal-weight men. Obesity may contribute to cancer by increasing blood levels of sex hormones or insulin.

Use our BMI calculator to find out if you weight too much for your height.

Binge drinking

Men who binge drink increase their risk of getting prostate cancer, while men who regularly drink moderate or even heavy amounts of alcohol don't expose themselves to the same danger, according to new research. Several previous studies have noted that an increased risk of prostate cancer among men who consume a lot of alcohol or who have been long-time drinkers, but none examined drinking patterns.

Researchers evaluated the association between drinking habits and the risk of prostate cancer among nearly 48,000 men over a 12-year period. Men who regularly drank large quantities of alcohol and men who were former drinkers were at no greater risk for prostate cancer than nondrinkers or men who drank less than one day a week. But for men who went on drinking binges—consuming the equivalent of at least eight cans of beer in just a day or two—increased their risk by 64 percent over nondrinkers. The association between alcohol intake and prostate cancer was strongest among men with Type II diabetes.

Overall, the authors concluded, alcohol doesn't appear to contribute to prostate cancer risk, except for men who infrequently drink large amounts. The results warrant further evaluation.

Finasteride

Finasteride (Proscar), which is used to treat benign prostatic hyperplasia (BPH), has been hypothesized to decrease the risk of prostate cancer. (BPH is the noncancerous enlargement of the prostate gland due to an increase in the number of prostate cells.) However, a 2003 study found that although finasteride does appear to reduce the overall risk of prostate cancer, it seems to increase the risk of high-grade prostate cancer. After seven years, 18.4 percent of the men taking finasteride developed prostate cancer, compared with 24.4 percent of men taking a placebo. However, more serious tumors (Gleason score of 7 to 10) occurred in 6.4 percent of the finasteride group, compared with 5.1 percent of the placebo group. Based on these findings, men should not take finasteride solely to prevent prostate cancer, and men taking finasteride for BPH should undergo careful monitoring for cancer.