To Örebro University

BACKGROUND: Prostate cancer (PCa) is one of the most frequently diagnosed cancers in the world. Emerging evidence suggests that inflammatory cells such as M2 macrophages and regulatory T cells (T_regs) can contribute to cancer progression by suppressing the anti‐tumor immune response. This study investigated the number of CD163‐positive M2 macrophages in PCa tissue. It also investigated the correlation and interaction of M2 macrophages and T_regs.

METHODS: were assessed using Spearman's rank-order correlation and a likelihood test, respectively. Logistic regression was used to estimate odds ratios (ORs) for lethal PCa and macrophage counts.

RESULTS: showed a significant correlation (P < 0.001) but no interactions. The OR for lethal PCa was 1.93 (95%CI: 1.23-3.03) for men with high numbers of M2 macrophages. Also for cases with uncertain outcome (GS categories 3 + 4 and 4 + 3) high numbers of M2 macrophages does predict a poorer prognosis.

CONCLUSIONS: Our data showed that men with high numbers of M2 macrophages in the prostate tumor environment had increased odds of dying of PCa. It is possible that M2 macrophages, together with other suppressor cells such as T_regs , promote an immunosuppressive environment.