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 LNs. 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.