Infiltration of tumour‐associated macrophages in prostate biopsy specimens is predictive of disease progression after hormonal therapy for prostate cancer

Study Type – Prognostic (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? In general, tumour‐associated macrophage (TAM) is important for tumour progression including prostate cancer. In this paper, we clarified the usefulness of TAM in prostate biopsy specimens for predicting prognosis after hormonal therapy. OBJECTIVE • To evaluate tumour‐associated macrophage (TAM) infiltration in prostate biopsy specimens as a possible prognostic factor for prostate cancer (PCa) after hormonal therapy. PATIENTS AND METHODS • Immunostaining of TAMs in prostate biopsy specimens was performed using a monoclonal antibody CD68 for 71 patients having PCa treated with hormonal therapy. • Six microscopic (×400) fields around the cancer foci were selected for TAM counting. RESULTS • The median value of serum prostate‐specific antigen (PSA) was 50.1 ng/mL, and the median TAM count was 22. • Recurrence‐free survival was significantly better in patients with fewer TAMs (<22) than in those with higher numbers of TAMs (≥22) ( P < 0.001). • TAM count was higher in those with higher serum PSA (PSA), higher Gleason score, clinical T stage or those with PSA failure. Cox multivariate analysis showed that TAM count is one of the prognostic factors for PCa treated by hormonal therapy ( P < 0.0001). CONCLUSION • TAM infiltration in prostate needle biopsy specimens is a useful predictive factor for PSA failure or progression of PCa after hormonal therapy.