High dietary intake of saturated fat was associated with more aggressive prostate cancers in a new study of US men published online September 6 in Prostate Cancer and Prostatic Diseases.
There was also a suggestion of a stronger association among men who did not take statins, which mitigate the effect of fat-related cholesterol, reported the study authors, led by Emma Allott, PhD, an assistant professor of nutrition at the University of North Carolina at Chapel Hill.
The tie between saturated fat intake and prostate cancer was also more pronounced among white Americans, said the study authors.
"Our findings suggest that limiting dietary intake of saturated fat, clearly important for cardiovascular disease prevention, may also have a role in aggressive prostate cancer prevention," Dr Allott told Medscape Medical News.
She explained that saturated fats are commonly found in animal products, including meat and dairy.
Dr Allott and her coinvestigators observe that saturated fat intake affects cholesterol levels, which, in turn, have been tied to prostate cancer development in epidemiological and laboratory studies.
So the team investigated a possible saturated fat–prostate cancer link by using data from the North Carolina-Louisiana Prostate Cancer Project on 1854 men with newly diagnosed prostate cancer.
This cohort included 321 men with "highly aggressive" prostate cancers, which were defined as having a Gleason score of 8 or greater, a prostate-specific antigen level greater than 20 ng/mL, or a Gleason score of 7 or greater with stage T3-T4 disease.
The rest of the men in the study, all with intermediate- and low-risk prostate cancers, were used as the referent group to examine the association between tertiles of fat intake and aggressive prostate cancer.
Using baseline information collected on each project participant's diet, the researchers calculated the levels of saturated fat in each man's diet.
In a secondary analysis, they also calculated levels of mono-unsaturated and poly-unsaturated fatty acids (MUFAs and PUFAs), the types found in vegetable oils or fish, as well as levels of cholesterol and trans fats and their relation to aggressive prostate cancer.
They found that a high total fat-adjusted saturated fat intake was associated with an elevated odds ratio (OR) for aggressive prostate cancer (OR, 1.51; 95% confidence interval [CI], 1.10 - 2.06; P trend = .009). However, a high total fat-adjusted saturated fat intake had only an attenuated, nonsignificant association in statin users (OR, 1.16; 95% CI, 0.67 - 2.01; P trend = .661). This latter finding led the researchers to say there was a "suggestion of a stronger [protective] effect in men not using statins."
There were no statistically significant associations between aggressive prostate cancer and PUFA and MUFA intake, or trans fats intake.
But a high level of total cholesterol intake was associated with aggressive prostate cancer in white Americans (OR, 1.62; 95% CI, 1.02 - 2.58; P trend = .056). This significant association was not seen in black Americans.
"In summary, we found that both the total amount and the composition of dietary fat impacted PC [prostate cancer] aggressiveness," conclude the study authors.
An expert not involved with the study agreed.
"The study supports a role of saturated fat in prostate cancer progression," said Pao-Hwa Lin, PhD, associate professor of medicine, Duke University Medical Center, who was asked for comment.
"However, this study is still observational in nature and thus cannot provide definitive conclusion," she added.
This is not a widely studied subject, said Dr Lin. "Not many studies have examined this question specifically, but many have examined the relationship of fish oil and prostate cancer risk or its progression."
Dr Lin described one study published in 2015 that examined the consumption of saturated fat after prostate cancer diagnosis and the risk for death (Cancer Causes Control. 2015;26:1117-1126).
"They found that saturated fat intake was associated with a higher risk of all-cause mortality, while vegetable fat intake was associated with a lower risk. Men who consumed 10% fewer calories from animal fat and 10% more calories from vegetable fat after diagnosis had a 44% lower risk of mortality," she summarized.
The authors and Dr Lin have disclosed no relevant financial relationships.
Prostate Cancer Prostat Dis. Published online September 6, 2016. Full text
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Cite this: Dietary Saturated Fats Tied to Aggressive Prostate Cancer - Medscape - Oct 13, 2016.