Obesity increases men's risk of dying from prostate cancer
Overweight men are at an increased risk for developing prostate cancer, according to a new study published Tuesday in published on Tuesday in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
“It is absolutely clear that obesity increases a man’s risk of dying from prostate cancer,” said Dr. Andrew Rundle, who conducted the study and is an associate professor of epidemiology at Columbia University’s Mailman School of Public Health in New York City.
What remains unclear, however, is if obesity causes prostate cancer.
“We don’t know if obesity causes it or makes it harder to treat,” Rundle said in an interview with NBC News.
As Rundle pointed out, being overweight is known to cause five cancers: post-menopausal breast cancer, colon cancer, kidney cancer, endometrial cancer and esophageal cancer. In men, prostate cancer is the leading diagnosed cancer, with lung cancer coming in second.
The prostate is the gland that releases the male hormone, testosterone, into the body. According to the American Cancer Society, 28,000 men in the U.S. died of prostate cancer in 2012, and over 238,000 new cases will be diagnosed this year in the U.S. alone.
"Studies conducted in the past have attempted to determine if there are subpopulations of men diagnosed with benign conditions that may be at a greater risk for developing prostate cancer,” Rundle said. “This is one of the first studies to assess the association between obesity and precancerous abnormalities."
For the study, Rundle and his colleagues looked at rates for obesity and future prostate cancer in 6,692 men. After a biopsy or transurethral resection of the prostate with benign findings, they followed the men for 14 years. To determine obesity, the research team used the standard Body Mass Index (BMI), which factors in weight and height combined. Given the average BMI of 30, approximately one-third of the U.S population is considered obese, according to Rundle.
Rundle’s team conducted a case-control study among 494 of these patients and 494 matched controls. As a result, they discovered a significant link between obesity and precancerous abnormalities, as precancerous abnormalities were present in 11 percent of the patients' benign specimens.
Indeed, the researchers found that obesity at the time of the initial procedure was associated with a 57 percent increased incidence of prostate cancer during follow-up.
If a rectal examination indicates a hardening of the prostrate, or if PSA levels are high, a physician will usually schedule a biopsy to test for cancerous cells. However, biopsies can miss cancerous cells and therefore cause inaccurate results, depending on which tissues were taken during the biopsy.
“It is possible that the tumors missed by initial biopsy grew and were detected in a follow-up biopsy," Rundle said. So what can a man do to prevent prostate cancer? The AARP offers the following 5 tips from researchers and health experts to help men lower their risk of getting prostate cancer:
1. The right diet: beyond marinara sauce
For years, men who wanted to lower their risk for prostate cancer were advised to eat more cooked tomatoes, which are rich in lycopene, an antioxidant that appears to fight tumors. Today some health experts say that changing your diet could cut the risk for prostate cancer by as much as 30 percent to 50 percent.
Fill up on:
• Fish. The omega-3 fatty acids in fish — especially oily varieties such as salmon and mackerel — dampen inflammation, which appears to promote prostate tumors. In one recent study, men who ate oily fish more than once a week reduced their risk for developing aggressive prostate cancer by 57 percent.
• Leafy greens. Eating several servings of spinach and other leafy greens per week may cut the risk of prostate cancer. Filling up on beans, summer squash, garlic, red peppers, berries and orange melon may also help.
• Coffee. A recent Harvard University study found that men who drink at least six cups of coffee a day were 60 percent less likely to develop lethal prostate cancer. Fortunately, decaffeinated coffee appeared to be just as effective as the high-test variety.
Cut back on:
• Simple carbohydrates. Sugary candy and soda, as well as starchy foods such as white bread and white rice are all high-glycemic carbs, which spark inflammation. One recent study found that men who ate the most sweet, starchy food were 64 percent more likely to develop advanced prostate cancer.
• Corn oil. It's a top source of omega-6 fatty acids, another trigger for inflammation that may promote prostate cancer.
• Well-done red meat. Well-done meats are loaded with cancer-causing compounds, says Witte. He recently completed a study showing that men who eat well-done beef several times a week may double their risk for aggressive prostate cancer. The increased risk of prostate cancer, he says, was specifically tied to the time and "doneness" of the red meat — the longer meat is exposed to heat, the more carcinogens form.
2. Supplements: Be wary
• If you still take vitamin E for prostate cancer, stop. There's no credible data that it or any other vitamin, mineral or medicinal herb prevents prostate cancer.
3. Drugs: benefits and risks?
• Some doctors give men at high risk for prostate cancer the drugs Proscar (finasteride) and Avodart (dutasteride), which reduce the threat by an estimated 23 percent.
• These drugs are normally prescribed for treating symptoms of an enlarged prostate and are not approved for cancer prevention by the U.S. Food and Drug Administration because studies show that men taking them who do end up getting diagnosed with prostate cancer are more likely to have a highly lethal form of the disease.
• But some physicians contend that increased risk may be a mirage. Instead of causing deadly cancer, they may simply make the disease easier to detect.
4. Exercise: Just do it anyway
• Although the general health benefits of exercise are beyond doubt, several large studies have failed to show that it lowers the risk for prostate cancer.
• One possible explanation: Healthy men who work out a lot may be more likely to get tested for prostate cancer. That could mask any potential protective effect of exercise.
5. Have sex: And have it often
• Finally, there's evidence that men who have frequent sexual intercourse often may lower their risk for prostate cancer, possibly because ejaculation cleans out cancer-causing compounds that can accumulate in the gland.
• A study involving more than 29,000 male doctors and other health professionals found that men who ejaculated at least 21 times a month cut their risk for prostate cancer by up to 33 percent compared with men who reported an average of four to seven ejaculations per month.
SOURCES: Cancer Epidemiology, Biomarkers April 23, 2013 (doi: 10.1158/1055-9965.EPI-12-0965). 5 Ways to Help Prevent Prostate Cancer, Timothy Gower, November 18, 2011.