The p16 Immunostaining Predicts the Risk of Recurrence in Prostate Cancer.

Objective: This study aimed to investigate the influence of p16 immunohistochemical expression on the biochemical recurrence rate of pT2-pT3 prostate cancer.

Materials and methods: A total of 488 pT2-pT3 stage prostate adenocarcinomas undergoing radical prostatectomy were included in this study. Following a review of Gleason classification and retrieval of sociodemographic and clinicopathological data, as well as the date of last consultation and biochemical recurrence, immunohistochemistry for p16 was performed. Data were associated using the chi-square test, Fisher's exact test, and multinomial logistic regression model.

Results: A total of 432(94.5%) cases showed positivity for p16 with an average of 37.38±27.32% positive cells and a mean histoscore of 2.70±2.24. A total of 117 (18.4%) patients experienced biochemical recurrence within three years, which was directly associated with high preoperative PSA (p=0.007), positive surgical margins (p<0.001), pT3 staging (p<0.001), nodal involvement (p<0.001), Gleason score > 3+4 (p<0.001), <50% positivity for p16 (p=0.035), and histoscore p16 =<3 (p=0.004). In multivariate analysis, Gleason score > 3+4 (HR = 3.08 (95% CI = 1.69-5.62), positive surgical margins (HR = 2.93 (95% CI = 1.70-5.04), and histoscore p16 =<3 (HR = 2.49 (95% CI = 1.17-5.32) were predictors of biochemical recurrence within three years.

Conclusion: p16 immunostaining, along with classical features such as Gleason Score and surgical margin involvement, are significant predictors of biochemical recurrence in pT2-pT3 prostate tumors.