Blood platelet volume predicts treatment-specific outcomes of metastatic castration-resistant prostate cancer.

BACKGROUND

In the present guidelines for the management of metastatic castration-resistant prostate cancer (mCRPC), it is unclear who benefits most from androgen receptor axis-targeted agents (ARATs) or docetaxel as the first-line treatment.

METHODS

We conducted a retrospective study to explore new treatment-specific biomarkers in mCRPC. A total of 211 patients with mCRPC who received either ARAT or docetaxel as first-line treatment were included. Patients were compared for radiographic progression and prostate-specific antigen (PSA) progression. Multivariable Cox regression models were used to assess the association between pretreatment biomarkers and risk of events. The statistical interaction between biomarkers and clinical outcomes was also evaluated.

RESULTS

Of all analyzed biomarkers, multivariable Cox regression models identified MPV [≤ median (9.7 fL)] as an independent prognostic factor of radiographic progression [hazard ratio (HR), 2.35; 95% confidence interval (CI), 1.15-4.80; P = 0.019] and PSA progression (HR, 1.96; 95% CI, 1.01-3.95; P = 0.048) in patients treated with ARAT, whereas such associations were not observed in those treated with docetaxel. Interaction analyses showed that those initially treated with docetaxel have lower risk of radiographic progression (HR, 0.33; 95% CI, 0.13-0.79; P = 0.014) and PSA progression (HR, 0.48; 95% CI, 0.23-0.98; P = 0.044) than ARAT when MPV was small.

CONCLUSIONS

The present study identified pretreatment MPV as a significant treatment-specific prognostic factor of PSA and radiographic progression in patients with mCRPC who received first-line treatment. Furthermore, our results suggested that those with small MPV may better be treated initially with docetaxel than ARAT.