Perineural invasion associated with increased cancer-specific mortality after external beam radiation therapy for men with low- and intermediate-risk prostate cancer

Purpose: To identify an association between perineural invasion (PNI) and cancer-specific survival in patients With prostate cancer after standard-dose external beam radiation therapy (RT). Methods and Materials: A total of 517 consecutive patients who underwent RT (median dose, 70.5 Gy) between 1989 and 2003 for low-risk or intermediate-risk prostate cancer were studied. A genitourinary pathologist (AAR) scored presence or absence of PNI on all prostate needle-biopsy specimens. A Cox regression multivariable analysis was performed to assess whether the presence of PNI was associated with risk of prostate cancer-specific mortality after RT when the recognized risk-group variables were factored into the model. Estimates of cancer-specific mortality were made using a cumulative incidence method. Comparisons of survival were made using a two-tailed log-rank test. Results: At a median follow-up of 4.5 years, 84 patients (16%) have died, 15 of 84 (18%) from prostate cancer. PNI was the only significant predictor of prostate cancer-specific mortality after RT (p = 0.012). The estimated prostate cancer-specific mortality was 14% at 8 years for PNI + patients vs. 5% for PNI- patients (p = 0.0008). Conclusions: Patients with low- or intermediate-risk prostate cancer who have PNI on prostate needle biopsy have a significantly higher rate of prostate cancer-specific mortality after standard-dose radiation therapy than patients without PNI. Although this analysis is retrospective, this association argues for consideration of the use of more aggressive therapy, such as hormonal therapy with RT or dose escalation, in these select patients. (c) 2006 Elsevier Inc.