Mitochondrial DNA copy number in leukocytes predicts long-term survival in prostate cancer

OBJECTIVES: Low mitochondrial DNA copy number (mtCN) in leukocytes is a predictor of all-cause mortality, independent of age and sex. For malignant diseases, results about the prognostic value of leukocyte mtCN have been conflicting. Aim of the present study was to analyze the prognostic value of mtCN for long-term prostate cancer survival. METHODS: Blood samples of prostate cancer patients were obtained before initiation of radiotherapy. Relative mtCN was determined by a quantitative polymerase chain reaction method in 662 patients with prostate cancer. Main outcome was overall survival. RESULTS: During a follow-up time of 120 months, 218 (32.9 %) patients died. In a univariate Cox regression analysis, higher mtCN z-score was significantly associated with lower overall mortality (hazard ratio 0.83, 95 % confidence interval 0.72-0.96; p=0.009). In a multivariate Cox regression model including age at diagnosis, androgen deprivation therapy, and risk group (based on PSA level, GS, and T stage), higher mtCN z-score remained a significant predictor of lower overall mortality (hazard ratio 0.85, 95 % confidence interval 0.74-0.98; p=0.029). CONCLUSIONS: High leukocyte mtCN predicts better overall survival in patients with prostate cancer.