Study Finds Prostate Cancer Survivors Who Maintained a Western Diet Had an Increased Risk of Death
A large study evaluating the relationship of dietary patterns with prostate cancer–specific and all-cause mortality among men diagnosed with nonmetastatic prostate cancer has found that the men who ate a Western-style diet of foods rich in processed meats, red meats, and high-fat dairy products had a 153% increased risk for prostate cancer–specific death and a 67% increased risk of death from all causes. Men who maintained a “Prudent” diet of vegetables, fruits, fish, legumes, and whole grains had a 36% lowered risk of death from all causes.
These findings suggest that modifications to diet after a prostate cancer diagnosis may influence survival and have a direct clinical translation. The study by Yang et al is published in Cancer Prevention Research.
Study Methodology
The researchers analyzed data on 926 men participating in the Physicians’ Health Study (PHS) I and II who had been diagnosed with nonmetastatic prostate cancer. One food-frequency questionnaire was sent to all PHS participants to collect information on usual diet between 1999 and 2002. The men were asked about their usual intake over the previous year of foods and beverages included in the questionnaire. Food items were classified into 39 predefined food groups to minimize within-person variation in intakes of individual foods. Dietary patterns were derived from these food groups through principal component analysis. Participants were also asked about their clinical status.
The researchers followed the patients for an average of 14 years following their prostate cancer diagnosis, and assessed the impact of dietary patterns on mortality after accounting for such factors as body mass index, smoking habits, prostate-specific antigen levels, tumor characteristics at diagnosis, and initial treatment.
The men were classified into quartiles of the Prudent and Western dietary patterns.
Study Findings
The researchers found that the Western pattern was significantly related to a higher risk of prostate cancer-specific and all-cause mortality. Comparing men in the highest vs the lowest quartile of the Western pattern, the hazard ratios (HRs) were 2.53 (95% confidence interval = 1.00–6.42; P = .02) for prostate cancer–specific mortality and 1.67 (95% CI = 1.16–2.42; P = .01) for all-cause mortality. The Prudent pattern was associated with a significantly lower all-cause mortality (HR quartile 4 vs quartile 1 = 0.64; 95% CI = 0.44–0.93; P= .02); the relationship with prostate cancer–specific mortality was inverse but not statistically significant.
A postdiagnostic Western dietary pattern was associated with higher prostate cancer–specific and all-cause mortality, whereas a Prudent dietary pattern was related to lower all-cause mortality after prostate cancer diagnosis.
A Word of Caution
“These findings suggest that modifications to diet after prostate cancer diagnosis may influence survival and have a direct clinical translation,” wrote the study authors.
“Nevertheless, given the scarcity of literature on the relation between post-diagnostic diet and prostate cancer progression, and the small number of disease-specific deaths in the current study, these associations, particularly those for disease-specific mortality, merit caution in their interpretation as well as further evaluation.”
In a statement, the first author of the study, Meng Yang, PhD, MPH, Research Fellow in the Department of Nutrition at Harvard T.H. Chan School of Public Health, said that because “Most men in the cohort are Caucasian and all are physicians … our results need to be replicated in independent populations with more diverse socioeconomic and racial/ethnic backgrounds.”
Dr. Yang and Jorge E. Chavarro, MD, ScD, of the Harvard T.H. Chan School of Public Health and Brigham and Women’s Hospital are corresponding authors of the Cancer Prevention Research article.
The 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 Cancer Center SPORE in Prostate Cancer.
The study authors reported no conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
