High Absolute Monocyte Count Predicts Poor Clinical Outcome in Patients with Castration-Resistant Prostate Cancer Treated with Docetaxel Chemotherapy.

Abstract

The association of peripheral monocyte count and prostate cancer progression is not well characterized. Our aim was to investigate the prognostic value of absolute monocyte count (AMC), which is thought to modulate immune response in the tumor microenvironment, in castration-resistant prostate cancer (CRPC) patients treated with docetaxel chemotherapy. We retrospectively reviewed the medical records of 214 CRPC patients who received docetaxel therapy and were used as the training and validation set. Docetaxel at a dose of 75 mg/m2 was administered every 3 or 4weeks. Clinicopathological factors and laboratory data were collected to assess the prognostic factors for overall survival (OS) and progression-free survival (PFS). In the training set, the median age was 73.0years, and the median prostate-specific antigen (PSA) value was 31.7 ng/ml at initial treatment. The median OS and PFS were 23.0 months (range 1.20-84.0) and 11.2 months (range 3.6-78.0), respectively. According to multivariable Cox regression analysis, AMC ≥400/uL, PSA level ≥20ng/ml, and Hb <10mg/dL were associated with increased risk of PSA progression [hazard ratio (HR) 2.06, p=0.005; HR 2.39, p=0.002; and HR2.38, p=0.024, respectively]. Moreover, multivariate analysis for OS indicated that AMC ≥400/uL, pretreatment PSA level ≥20ng/ml, presence of visceral metastasis, and alkaline phosphatase ≥284U/L were independent prognostic factors for shortened OS (HR2.07, p=0.004; HR2.18, p=0.007; HR 2.11, p=0.011; and HR 1.67, p=0.048, respectively). According to the validation set, high AMC remained an independent prognostic factor for PFS and OS (HR2.26, p=0.001; and HR3.10, p<0.001, respectively). Elevated monocyte counts were associated with aggressive tumor features and poor survival outcomes of patients with CRPC treated with docetaxel chemotherapy.