Tissue expression of IL16 in prostate cancer and its association with recurrence after radical prostatectomy

Genetic polymorphism located within the IL16 gene has been reported to be associated with aggressive prostate cancer (PCa). Our aim was to establish whether the tissue expression of IL16 is a prognostic factor of survival in PCa.

The files of patients who underwent radical prostatectomy (RP) between 1995 and 2001 were reviewed. The cases were selected and classified according to the D'Amico classification for risk of recurrence (intermediate or high). The value of IL16 and its receptor CCR5 (chemokine (C-C motif) receptor 5) expression levels were determined as witness of aggressiveness patterns and markers of biological relapse in patients with PCa treated by RP. A tissue microarray of 304 cases was constructed. IL16 and CCR5 expression levels were characterized by immunohistochemistry.

IL16 expression was correlated with high Gleason score (i.e., >7) (P < 0.01). It was not significant for CCR5. IL16 and CCR5 were not associated with prostate-specific antigen (PSA) or capsular extension of the disease. The accurate prediction of disease outcome, using stratification of cases, according to negative margins and D'Amico classification was significantly enhanced by status of IL16 expression (P ≤ 0.01). In univariate analyses, Gleason score, PSA level, stage and loss of IL16 expression were related to better biological-free survival (P < 0.05) but not CCR5. In a multivariate analysis, IL16 expression, Gleason score, and tumor stage were independent factors for biochemical-free survival (P = 0.001).

IL16 appears to be a useful prognostic factor in PCa. Its expression in PCa tissue was correlated to tumor aggressiveness and biochemical relapse of the disease.