A Healthy Life May Guard Against Aggressive Prostate Cancer

Megan Brooks

July 10, 2013

Men may be able to lower their risk of being diagnosed with highly aggressive prostate cancer by sticking closely to diet and exercise recommendations, new research hints.

In the study, researchers looked at the lifestyle and diet of more than 2000 men with newly diagnosed prostate cancer.

In a cross-sectional analysis, they found "clear inverse associations" between greater adherence to World Cancer Research Fund (WCRF) recommendations on diet and physical activity and the risk for aggressive prostate cancer at diagnosis.

The finding was statistically significant and similar among black and white men, despite black men having a higher risk for highly aggressive tumors. In particular, the researchers found that limiting consumption of red meat and avoiding an energy-rich diet were significantly protective against aggressive tumors.

The other WCRF recommendations include:

  • Maintain a body mass index (BMI) within normal range between 21 and 23 kg/m2

  • Engage in at least 60 minutes of moderate or 30 minutes of vigorous physical activity daily

  • Avoid sugary drinks

  • Eat at least 5 servings of nonstarchy vegetables and fruits daily

  • Eat at least 25 grams of unprocessed grains/cereals and legumes daily

  • Limit alcohol intake to 2 drinks per day for men and 1 drink per day for women

  • Limit sodium intake to less than 2.4 grams per day

The new study appears in the journal Nutrition and Cancer .

"Most men are at risk of prostate cancer, but it is the level of aggressiveness of disease that is most clinically relevant," lead investigator Lenore Arab, PhD, from the Jonsson Comprehensive Cancer Center at the University of California, Los Angeles, said in a statement.

Men who already have prostate cancer and are worried about a worsening of disease may also be positively instructed by the results, she added. "These findings [also] suggest that even men with prostate cancer can take control of their disease and moderate its aggressiveness through diet and lifestyle choices."

However, Dr. Arab and her colleagues say the "low level" of adherence to many of the WCRF recommendations observed in the study is a "concern."

Nicholas J. Ollberding, PhD, who wasn't involved in the study, is equally concerned that "few participants in this study were found to be adherent to the recommendations."

This finding "highlights the need for approaches to improve patterns of diet and physical activity in patients with prostate cancer and prostate cancer survivors," Dr. Ollberding told Medscape Medical News. He is an assistant professor of pediatrics in the Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, in Ohio.

Dr. Arab and colleagues examined associations between adherence to WCRF recommendations and risk for highly aggressive prostate cancer in 1064 black and 1088 white men aged 40 to 70 years with newly diagnosed prostate cancer participating in the North Carolina-Louisiana Prostate Cancer Project. They defined highly aggressive prostate cancer as Gleason sum >/= 8 or PSA > 20 ng/mL, or Gleason sum >/= 7 and clinical stage cT3-cT4.

In a multivariate model, greater adherence overall was inversely associated with highly aggressive prostate cancers (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.79 – 0.96). "In this model, the likelihood of highly aggressive tumors at diagnosis decreased 13% for each additional point increase in the total adherence score," the researchers say.

They also determined that the risk for highly aggressive prostate cancer at diagnosis was 38% higher among men who adhered to fewer than 4 of the 9 recommendations relative to those adhering to 4 or more recommendations (OR, 1.38; 95% CI, 1.10 -1.74). The results were similar for both black and white men.

The researchers identified 2 individual recommendations that significantly predicted a lower risk for highly aggressive disease: eating fewer than 500 grams of red meat each week (OR, 0.77; 95% CI, 0.61 – 0.98) and eating fewer than 125 total kilocalories (kcal) per 100 grams of food daily (OR, 0.71; 95% CI, 0.51 – 0.99).

Adherence Challenges

Adherence levels among the study subjects were low, as mentioned. For example, fewer than 5% of all the men were compliant with the recommended BMI of 21 to 23 kg/m2 and they fell way short of recommended physical activity recommendations.

Only 7.6% of the men got the recommended 30 minutes of vigorous exercise or at least 60 minutes of moderate exercise daily. Expanding the adherence definition to include those who got at least 15 minutes of vigorous exercise daily or at least 30 minutes of moderate exercise daily boosted the adherence rate to 21.1% overall.

Only 15.7% of men adhered to the recommendation to limit energy-dense foods to 125 kcal/100 grams or less. About 63% of the men said they ate at least 5 servings of fruits and nonstarchy vegetables daily, as recommended, but only 13.5% consumed at least 25 grams per day of legumes and unprocessed grains or cereals. Only 24% were adherent with the commendation to consume less than 2.4 grams of sodium per day.

Dr. Ollberding noted that the findings in this study are "in-line with previous longitudinal studies conducted in the US and Europe that have reported a lower risk of cancer and cancer death among individuals most adherent to the WCRF/AICR [American Institute for Cancer Research] 2007 recommendations."

Still, he said, "any causal inference is limited by the cross-sectional nature of the study."

He also noted that while many cancer patients report improvements in modifiable health behaviors including diet and physical activity after a diagnosis of cancer, "the extent to which cancer patients and survivors maintain these changes is unclear. Ongoing research in this area, including clinical trials designed to determine the impact of diet in relation to cancer survival, will provide a more detailed understanding and help to establish dietary guidelines for cancer patients and survivors," Dr. Ollberding said.

The study was supported by the US Department of Defense. The authors and Dr. Ollberding have disclosed no relevant financial relationships.

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