The prognostic value of inducible nitric oxide synthase in local prostate cancer

Objective To compare the clinical and histological data from patients with prostate cancer with the results of the immunohistochemical analysis of inducible nitric oxide synthase (iNOS), and thus determine the prognostic value of iNOS. Patients and methods The study included 82 patients (mean age 64.6 years, sd 6.1) with local prostate cancer treated by radical prostatectomy in two Finnish hospitals. Their mean ( sd) follow-up was 3.3 (2.2) years. An immunohistochemical method was used to detect the expression of iNOS in these specimens, and the expression graded according to staining intensity as none, weak or strong. Results There was weak or strong expression of iNOS in 25 (31%) and 56 (68%) of the patients, respectively, and one specimen was negative for iNOS. Strong expression of iNOS was related to high a preoperative prostate specific antigen (PSA) level (P = 0.006) and high pT classification (P < 0.001), but not to nodal status, grade, seminal vesicle or capsular invasion, surgical margin status, perineural infiltration, tumour infiltrating lymphocytes or proliferation rate of cancer cells. A PSA failure was detected in 29 patients but was not predicted by iNOS expression. A Cox multivariate analysis showed that surgical margin positivity, seminal vesicle involvement and number of tumour infiltrating lymphocytes predicted the PSA failure. Conclusion A high expression of iNOS was related to a high pT classification and the preoperative PSA level but not to other established prognostic factors; iNOS expression was not a predictor of PSA failure in patients with local prostate cancer.