CD8-positive T cells and CD204-positive M2-like macrophages predict postoperative prognosis of very high-risk prostate cancer.

To stratify the heterogeneity of prostate cancer (PCa) with seminal vesicle invasion (SVI) immunologically after radical prostatectomy focusing on the tumor microenvironment. We retrospectively reviewed the clinicopathological data of 71 PCa patients with SVI, which is known as a factor of very high-risk PCa. Preoperative clinical variables and postoperative pathological variables were evaluated as predictors of biochemical recurrence (BCR) with a multivariate logistic regression. Immune cell infiltration including the CD8-positive cell (CD8 cell) and CD204-positive M2-like macrophage (CD204 cell) was investigated by immunohistochemistry. The cumulative incidence and risk of BCR were assessed with a Kaplan-Meier analysis and competing risks regression. A higher CD8 cell count in the SVI area significantly indicated a favorable prognosis for cancers with SVI (p = 0.004). A lower CD204 cell count in the SVI area also significantly indicated a favorable prognosis for cancers with SVI (p = 0.004). Furthermore, the combination of the CD8 and CD204 cell infiltration ratio of the SVI area to the main tumor area was a significant factor for BCR in the patients with the PCa with SVI (p = 0.001). In PCa patients with SVI, the combination of CD8 and CD204 cell infiltration is useful to predict the prognosis.