Presence of prostate cancer metastasis correlates with lower lymph node reactivity

BACKGROUND. Several reports suggest that the dissemination of neoplastic cells and cancer progression are associated with the generation of an immunosuppressive environment. METHODS. In this report, we investigated immunological effects of prostate cancer by comparing metastastic and non-metastatic pelvic lymph nodes (LNs) from 25 patients with carcinomatous involvement of LNs to the non-metastatic LNs from 26 control patients with no metastatic involvement by immunohistochemistry and histological analyses. RESULTS. Our results showed a decreased abundance of CD20+ B lymphocytes (P = 0.031), CD38+ activated lymphocytes (P = 0.038), and CD68+ macrophages (P < 0.001), and less evidence of follicular hyperplasia (P = 0.014), sinus hyperplasia (P < 0.001), and fibrosis (P = 0.028) in metastatic LNs comparatively to control LN's. Finally, we observed that metastatic LNs were significantly smaller than control LNs (P = 0.005). CONCLUSIONS. Our results suggest that the development of prostate cancer LN metastasis is accompanied with smaller LN size and decreased LN reactivity suggesting the development of an immununosuppressive microenvironment.