Prognostic significance of p16 immunohistochemical expression in urothelial carcinoma

Abstract

Abstract Background p16 is the protein product of most commonly involved gene in bladder carcinogenesis. Therefore, we performed an immunohistochemical study to evaluate association of p16 overexpression with prognostic parameters in bladder cancer. Methods p16 immunohistochemistry was performed on 121 cases of bladder cancer and association with tumor grade, lamina propria invasion, muscularis propria invasion and survival status was noted. Results Low expression of p16 was noted in 86% (104 cases), whereas 14% (17 cases) revealed high p16 expression. We found significant association of p16 expression with tumor grade (p = 0.000), muscularis propria invasion (p = 0.001), lamina propria invasion (p = 0.001) and survival status (p = 0.020). Univariate binary logistics showed that low grade tumors were less likely to express high p16 expression as compared to high grade tumors. Similarly, patients with lamina propria and muscularis propria invasion were more likely to exhibit high p16 expression. Significant association of high p16 expression was noted with worse long term survival (p = 0.020), while univariate logistic regression showed that patients with low p16 expression were at low risk (HR = 0.194) to die of disease as compared to patients with high p16 expression. Conclusion p16 is an important biomarker in bladder cancer as it can be used for prognostic stratification of patients with bladder cancer. Moreover, we suggest that molecular studies should be performed in our population in order to correlate abnormal p16 expression with underlying gene mutations.

Keywords

• Bladder cancer
• p16
• Urothelial carcinoma
• Muscularis propria invasion