Original articleDietary patterns based on the Mediterranean diet and DASH diet are inversely associated with high aggressive prostate cancer in PCaP
Introduction
Prostate cancer accounts for the highest number of incident cancer cases and is the second leading cause of cancer death among American men [1]. Diet has been implicated in the development of prostate cancer [2], [3], [4], [5]. Fats (particularly animal fats), dairy, and calcium have been linked with an increased risk of prostate cancer [6], [7], [8], whereas high intakes of soy, fiber, fruits and vegetables, and tomato products (as a source of lycopene) have been inversely associated with prostate cancer [9], [10], [11], although a recent pooled analysis found no association with fruits, vegetables, or mature beans [12]. Patterns of overall dietary intake in relation to prostate cancer risk have been examined because foods and nutrients are not consumed singularly, but with conflicting results; less is known about the relationship between dietary patterns and prostate cancer aggressiveness [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23].
The Mediterranean diet (MED) and the Dietary Approaches to Stop Hypertension (DASH) diet are two a priori dietary patterns that promote high intakes of foods and nutrients beneficial for overall health. High MED scores have been linked to a decreased incidence of colorectal, breast, and prostate cancers [23], [24]. Although many studies have found no significant association between MED scores and prostate cancer aggressiveness [15], [17], [20], [21], [25], recent findings indicate high conformity to a Mediterranean-style diet is associated with lower risk of aggressive prostate cancer [26]. No published study has examined the association between the DASH diet and prostate cancer. In accordance with available evidence, the low intakes of meat, saturated fats, and full-fat dairy, combined with the high fiber, fruit, and vegetable intake characteristics of the MED and DASH diets have a biological basis for decreasing prostate cancer risk, and may confer protection against aggressive forms of prostate cancer [27], [28], [29], [30].
Five-year survival rates for local and regional stage diagnoses of prostate cancer remain high, but distant stage prostate cancers have a 28% 5-year survival rate [1]. Mortality rates also vary by race: African American (AA) men are almost twice as likely as European American (EA) or Hispanic men to die of prostate cancer, in part because they are more likely to be diagnosed with more aggressive forms of prostate cancer [31]. Improving diet quality among high-risk men, specifically AAs, may be a means for reducing these disparities. The purpose of this case-only study was to examine the association between dietary patterns, measured using MED and DASH scores, and prostate cancer aggressiveness by race.
Section snippets
Study population
Data were used from the North Carolina–Louisiana Prostate Cancer Project (PCaP), a cross-sectional, population-based, case-only, incident prostate cancer study designed to investigate racial differences in prostate cancer aggressiveness between AAs and EAs. Men with a first diagnosis of histologically confirmed adenocarcinoma of the prostate between July 1, 2004, and August 31, 2009, were eligible to participate if they met the following criteria: aged 40–79 years at diagnosis, not
Results
The final sample size included 1899 research subjects, with 1567 low-intermediate aggressive cases and 332 high aggressive cases of prostate cancer. Within the sample, 908 of the research subjects identified as AA (47.8%) and 991 identified as EA (52.2%). MED scores had an overall mean and SD of 4.19 ± 1.65. DASH scores had an overall mean and SD of 22.01 ± 4.37. Neither MED nor DASH scores displayed visible departure from normality. Research subjects diagnosed with high aggressive prostate
Discussion
In the PCaP study, research subjects who consumed a diet more closely aligned with the Mediterranean or DASH diets had decreased odds of high aggressive versus low-intermediate aggressive prostate cancer at diagnosis. Associations were similar for AAs and EAs, although they appeared to differ by age. Research subjects aged greater than or equal to 65 years had stronger inverse associations between the MED score and high aggressive prostate cancer than younger subjects. We noted patterns of
Conclusions
The results of this study suggest a protective effect of consuming a Mediterranean-style diet, and possibly the DASH diet, against aggressive prostate cancer diagnosis. Further research is needed to corroborate these findings and to better understand how diet may influence racial disparities in prostate cancer aggressiveness.
Acknowledgments
The North Carolina–Louisiana Prostate Cancer Project (PCaP) is carried out as a collaborative study supported by the Department of Defense, USA contract DAMD 17-03-2-0052. The authors thank the staff, advisory committees, and research subjects participating in the PCaP study for their important contributions.
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Conflicts of interest: All listed authors meet the authorship criteria and no individual meeting authorship criterion has been omitted. This work represents the original work of the authors and is not currently under consideration elsewhere, nor has it been previously published in the same or similar form and no copyright to any other work was breached in the article’s creation. The authors declare no conflict of interest.