Plasma Fatty Acids as Surrogate for Prostate Levels

ABSTRACT

Inconsistent results from epidemiologic studies of circulating fatty acids and prostate cancer risk may be partly due to use of blood concentrations as surrogate biomarkers of prostate tissue concentrations. To determine whether blood concentrations reflect prostate tissue fatty acid profiles, we evaluated associations between phospholipid fatty acid (PLFA) profiles measured in plasma and prostate tissue from 20 patients who underwent prostatectomy. For each patient, three prostate tissue specimens varying in size and location were collected. Correlations were calculated between a) tissue specimens by size ( ≤ 20 mg, > 20 mg); b) individual tissue samples [Intraclass Correlation Coefficient (ICC)]; and c) plasma and mean tissue PLFA concentrations. PLFA concentrations from ≤ 20 mg and > 20 mg tissues were nearly identical. For most PLFAs, intra-individual correlations between tissue specimens were moderate to strong (linoleic acid = 0.66, eicosapentaenoic acid = 0.96), with only one ICC below 0.50 (trans-fatty acid 18:2, ICC = 0.28). Most correlations of mean tissue and plasma concentrations were moderate to strong (α-linoleic acid = 0.47, eicosapentaenoic acid = 0.93). PLFA concentrations are largely homogeneous within the prostate and can be reliably measured in small quantities of tissue. The overall strong correlations between plasma and tissue suggest that for most individual PLFAs, plasma concentrations are adequate surrogate markers of prostate tissue concentrations.

Acknowledgments

We would like to acknowledge the participating patients, and physicians: Drs. Paul Lange, Jonathan Wright, William Ellis, Bruce Dalkin, and John Gore. We would also like to thank Dr. Lawrence True, Jennifer Noteboom, Lori Kollath, and the tissue acquisition team in the Department of Urology, School of Medicine, University of Washington

Statement of Authors' Contributions to Manuscript

J.M.S. and M.L.N. designed research; J.M.S., X.S., M.L.N., C.M., R.L.V., and D.W.L. conducted research, J.M.S. analyzed data, J.M.S., M.L.N, and X.S. wrote paper; J.M.S. had primary responsibility for final content. All authors have read and approved the final manuscript.

Conflict of Interest

The authors declare no potential conflicts of interest.

Additional information

Funding

This study is the result of work supported by the Pacific Northwest Prostate Cancer SPORE (P50CA97186) and by the Fred Hutchinson Cancer Research Center.