Background: It has been shown that neutrophil count or an elevated neutrophil-to-lymphocyte ratio (NLR) as well as testosterone levels are separately associated with increased mortality in patients with localized prostate cancer.
Objective: We tested a combination of testosterone levels and white blood cell (WBC) counts to predict overall survival (OS) in a prospective cohort of patients treated with radiotherapy for localized prostate cancer.
Patients and methods: The 381 patients included in this study were prospectively enrolled in phase 2 or 3 studies. Multivariate Cox proportional hazards models were used to analyze the influence of WBC count and testosterone level on biochemical recurrence and OS. Cutoff levels of ≤10.4 nmol/L (300 ng/dL) for testosterone and a median value of 6.2 (×109/L) for WBC count were used.
Results: The median follow-up for biochemical recurrence and OS were 72 and 78 months, respectively. A WBC count of ≥6.2 alone was not associated with OS (hazard ratio [HR] 0.66; 95% confidence interval [CI] 0.30-1.46). When combined with a testosterone level of >10.3 nmol/L, a WBC count of ≥6.2 was associated with increased mortality (HR 2.96; 95% CI 1.45-6.06) when compared with a WBC count of <6.2 (p-interaction = 0.01). The HR for biochemical recurrence for patients with a testosterone level >10.3 nmol/L combined with a lymphocyte level above or equal to the median was nearly identical to the HR of a testosterone level >10.3 nmol/L with a WBC above or equal to the median. There was no association between testosterone level and the NLR.
Conclusions: A high WBC and lymphocyte count combined with normal testosterone levels increases the overall mortality of patients treated with radiotherapy for localized prostate cancer within the first 6-7 years post-treatment. Validation in larger cohorts is necessary.