“We found that men diagnosed with nonmetastatic prostate cancer whose diet was more ‘Westernized,’ i.e., contained processed meats, refined grains, potatoes, and high-fat dairy, were more likely to die of prostate cancer,” said senior author Jorge E. Chavarro, MD, ScD, assistant professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health and of medicine at Brigham and Women’s Hospital, a teaching hospital of Harvard Medical School in Boston.
There are nearly 3 million men living with prostate cancer in the United States; however, there is very little information for patients and clinicians about how to manage patients’ lifestyles, such as diet, after a prostate cancer diagnosis to improve survivorship, which the authors sought to explore in this study, Chavarro explained.
Compared with men who were in the lowest quartile of the Western diet pattern, those in the highest quartile of the Western diet pattern had a 2.53 times (153 percent) increased risk for prostate cancer-specific death, and a 67 percent increased risk for death from all causes. Men whose diet was predominantly vegetables, fruits, fish, legumes, and whole grains, called the “prudent” diet pattern, had a 36 percent lowered risk for death from all causes; they also had a lowered risk for prostate cancer-specific death, but this association was not statistically significant.
“Because cardiovascular disease is one of the top causes of death among prostate cancer survivors, our findings regarding all-cause mortality are what we anticipated and closely align with the current knowledge of the role of diet on cardiovascular disease. Our findings with Western diet and prostate cancer-specific mortality, however, were surprising, in part because there are very little data regarding how diet after diagnosis may impact disease prognosis,” Chavarro said.
Chavarro, lead author of this study; Meng Yang, PhD, MPH, a research fellow in nutrition at Harvard Chan School; and colleagues used data from participants of the Physician’s Health Study I and II, who had completed a comprehensive questionnaire about their clinical status and diet. The researchers followed the patients for an average of 14 years after their prostate cancer diagnosis, and assessed the impact of dietary patterns on mortality after accounting for factors including body mass index, smoking status, prostate-specific antigen levels, tumor characteristics at diagnosis, and initial treatment.
“Our results suggest that the same dietary recommendations that are made to the general population primarily for the prevention of cardiovascular disease may also decrease the risk of dying from prostate cancer among men initially diagnosed with nonmetastatic disease,” Chavarro said.
“Most men in the cohort are Caucasian and all are physicians; therefore, our results need to be replicated in independent populations with more diverse socioeconomic and racial/ethnic backgrounds,” Yang cautioned.
This study was funded by the U.S. Department of Defense, the National Institutes of Health, the Prostate Cancer Foundation, the Boston Nutrition and Obesity Research Center, the Harvard TREC Center, and the Dana Farber/Harvard Cancer Center SPORE in Prostate Cancer. Chavarro and Yang declare no conflicts of interest.