Study Reinforces CVD, Other Non-Cancer Causes of Death in Men With Prostate Cancer

Men with nonmetastatic prostate cancer lived longer if they followed a healthier lifestyle, despite no reduction in prostate cancer-specific mortality, according to a large observational study.

A higher prostate cancer behavior score was associated with a 31% reduction in the hazard for all-cause mortality and a 33% reduction in the hazard for cardiovascular disease (CVD)-related mortality. African-American men, but not those in other racial/ethnic groups, also had a reduced risk of prostate cancer death.

On the other hand, a higher score on a hyperinsulinemia index was positively associated with all-cause and CVD-related mortality, whereas men who adhered to a plant-based diet had a lower all-cause mortality and a trend toward lower CVD-related mortality.

The findings add to existing evidence regarding a healthier lifestyle and better outcomes in prostate cancer and affirm the major contribution of non-cancer causes to overall mortality, reported Christopher A. Haiman, ScD, of the University of Southern California Keck School of Medicine in Los Angeles, and co-authors in JAMA Network Open.

“Notably, 85% of the observed deaths during follow-up were due to causes other than PCa [prostate cancer], highlighting the importance of managing comorbidities,” the authors concluded. “Further research is warranted to assess the potential benefits of health behavior counseling for men with nonmetastatic PCa in managing comorbidities and reducing the risk of death.”

Following a diagnosis of prostate cancer, many men want to know what they can do to improve their prognosis, said J. Ryan Mark, MD, of Fox Chase Cancer Center in Philadelphia.

“My common response is, ‘What’s good for your heart is good for your prostate,'” Mark, who was not involved in the study, told MedPage Today.

The study’s lack of data on prostate cancer recurrence or progression limits interpretation of the diet and lifestyle factors’ influence on prostate cancer outcomes.

“Nevertheless, the trends identified in this research offer valuable insights for designing future studies that explore the role of healthy living in diverse populations,” said Mark. “More immediately, they provide additional evidence to support the guidance we offer patients at a time when they may be most receptive to adopting healthier habits.”

Data from epidemiologic studies of modifiable factors and prostate cancer outcomes remain inconclusive, Haiman and co-authors noted in their introduction. Available evidence suggests smoking and a high-fat diet increase all-cause and prostate cancer-specific mortality, whereas physical activity has been linked to quality-of-life benefits and a reduced risk of prostate cancer death.

Obesity has been linked to poor prognosis, but the association is limited after accounting for pathologic characteristics of prostate cancer, the authors continued. Specific dietary factors, particularly increased consumption of certain vegetables, have shown potential for contributing to improved prostate cancer survival, but findings lack replication. Lifestyle and dietary indices have yielded suggestive information about potential salutary effects on prostate cancer outcomes, but limited evidence has accumulated from racially and ethnically diverse populations.

In an effort to address some of the limitations of existing evidence, Haiman and colleagues analyzed data from the Multiethnic Cohort (MEC) involving more than 215,000 adults ages 45-75 who were enrolled from 1993 to 1996 in California and Hawaii. The query identified 6,764 men who had prostate cancer diagnoses during 2003-2008 and were followed until death or loss to follow-up.

All participants in MEC completed a questionnaire at enrollment, providing general information, as well as lifestyle and dietary habits. The men with prostate cancer completed a follow-up questionnaire during 2003-2008 to update medical conditions and dietary/lifestyle behaviors. The final analysis included 2,603 men with nonmetastatic prostate cancer and complete information. Japanese Americans accounted for 29% of the study population, 24.8% were white, 22.2% were Latino, 19.1% were African American, and 5% were Native Hawaiian.

The investigators used two versions of the PCa Behavior Score to evaluate lifestyle factors and 13 predefined dietary quality indices, prioritizing four that correlated well with the others.

The men with prostate cancer had a median age of 69.6 and median follow-up of 10.9 years, during which 1,346 died. CVD was the cause of death in 24.6% of cases and prostate cancer was the cause in 14.6%.

The results showed that each 1-point improvement in the PCa Behavior Score was associated with a significant reduction in the all-cause mortality hazard (HR 0.69, 95% CI 0.63-0.77) and the CVD-related mortality hazard (HR 0.67, 95% CI 0.56-0.79). Improvement in the behavior score was associated with a 54% reduction in the prostate cancer-specific mortality hazard (95% CI 0.24-0.88) among African-American men but not other racial/ethnic groups.

A higher score on the Empirical Dietary Index for Hyperinsulinemia had a positive association with all-cause mortality (HR 1.37, 95% CI 1.02-1.84) and CVD-related mortality (HR 1.96, 95% CI 1.15-3.33). In contrast, a higher score on the Healthful Plant-Based Diet Index was associated with a reduced hazard for all-cause mortality (HR 0.75, 95% CI 0.58-0.97) and a trend toward a lower CVD-related mortality hazard (HR 0.67, 95% CI 0.44-1.03). None of the other lifestyle or dietary indices had significant correlations with mortality risk.

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