Methods
We conducted a nested case–control study (793 cases and 790 controls) of men randomized to the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) to evaluate the association between pre-diagnosis mtDNA copy number, measured in peripheral blood leukocytes, and the risk of PCa. We used logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) and polytomous logistic regression to analyze differences in associations by non-aggressive (Stage I/II AND Gleason grade?
Results
Although mtDNA copy number was not significantly associated with PCa risk overall (OR 1.23, 95% CI 0.97–1.55, p?=?0.089), increasing mtDNA copy number was associated with an increased risk of non-aggressive PCa (OR 1.29, 95% CI 1.01–1.65, p?=?0.044) compared to controls. No association was observed with aggressive PCa (OR 1.02, 95% CI?0.64–1.63, p?=?0.933). Higher mtDNA copy number was also associated with increased PSA levels among controls (p?=?0.014).Conclusions
These results suggest that alterations in mtDNA copy number may reflect disruption of the normal prostate glandular architecture seen in early-stage disease, as opposed to reflecting the large number of tumor cells seen with advanced PCa.