Prognostic significance of perineural invasion in localized prostate cancer.

Abstract

30 Background: While perineural invasion (PNI) has been associated with poorer clinical outcomes in prostate cancer patients, it is not well defined as a predictor of long-term endpoints in newly diagnosed prostate cancer. Therefore, we evaluated the role of PNI as a prognostic marker in patients with localized prostate cancer who underwent surgery or radiation. Methods: We analyzed a prospectively collected cohort of 5,034 consecutive patients with localized prostate cancer treated with surgery (n = 4,207) or radiation (n = 827) at University of Michigan from 1994-2013. The primary outcome measured was metastasis-free survival, with secondary outcomes of PSA-recurrence free survival and overall survival (OS). Covariates included age, treatment year, race, comorbidity index, pre-treatment PSA, Gleason score, and T-stage. Survival analysis was estimated using the Kaplan-Meir method, and multivariable analysis was performed using a Cox proportional hazards model. Results: 22.6% of surgery patients and 37.5% of radiation patients had PNI. 169 patients developed metastasis a median of 44 months (IQR 21-83 months) after primary therapy. In the combined cohort, PNI was a predictor of metastasis and PSA recurrence, but not OS (Table 1). For surgery, PNI was a predictor of metastasis, PSA recurrence, and OS. For radiation, PNI was a predictor of metastasis and PSA recurrence, but not OS. Conclusions: PNI is an independent predictor of long-term outcomes in newly diagnosed prostate cancer patients regardless of subsequent therapy. These data support the importance of PNI as a key factor denoting potentially aggressive prostate cancer and importing a significant increase in the likelihood of eventual metastatic progression. [Table: see text]