Prognostic value of tumor-associated macrophage count in human bladder cancer

Background: We determined the tumor-associated macrophage (TAM) count to investigate its importance in predicting clinical outcome or prognosis in patients with bladder cancer. Methods: The TAM count and microvessel count (MVC) were determined immunohistochemically in 63 patients with bladder cancer, including 40 superficial bladder cancers and 23 invasive bladder cancers. To examine the relationship between TAM count and clinical outcome or prognosis in bladder cancer, cystectomy rates, distant metastasis rates, vascular invasion rates and 5 year survival rates were compared between patients with low (< 67) and high (greater than or equal to 67) TAM counts. Results: The TAM count in invasive bladder cancers (154.22 +/- 11.98) was significantly higher than in superficial bladder cancers (49.05 +/- 7.76; P < 0.0001). The MVC in invasive bladder cancers (71.55 +/- 10.44) was also significantly higher than in superficial bladder cancers (47.02 +/- 5.57; P < 0.05). There was a positive correlation between TAM count and MVC (r = 0.30; P = 0.02). Immunohistochemical staining using CD68/horseradish peroxidase monoclonal antibody showed more infiltrating cells in invasive than superficial bladder cancers. Patients with a high TAM count (greater than or equal to 67) showed significantly higher rates of cystectomy, distant metastasis and vascular invasion than those with a lower TAM count (< 67). The 5 year survival rate estimated using the Kaplan- Meier method was significantly lower in patients with a high TAM count than in those with a low TAM count (P < 0.0001). Conclusions: Our results suggest that determination of TAM count in bladder cancer tissues is of value to predict the clinical outcome or prognosis and to select appropriate treatment strategies in patients with bladder cancer.