The prognostic significance of p63 cytoplasmic expression in colorectal cancer. An immunohistochemical study.

Objectives:   To evaluate p63 expression pattern in Saudi colorectal cancer (CRC) patients and correlate that with clinicopathological parameters and its role in carcinogenesis and prognosis.

Methods: Archival tumor samples were analyzed by immunohistochemistry for p63 expression in 324 consecutive Saudi patients diagnosed with CRC between January 2006 and December 2017 at the Pathology Department of a tertiary care Hospital, Madinah, Saudi Arabia.

Results: P63 over-expression was absent in normal mucosa, while 12.5% cases of adenoma showed its over-expression. In CRC, p63 expression was high in 24.1% of cases. There were no significant correlations between p63 expression and gender, tumor location, tumor size and tumor histologic differentiation. However, high p63 expression revealed a significant correlation with age (p=0.035), tumor type (p=0.004), American Joint Committee on Cancer stage (p=0.046), lymph node metastasis (p=0.006), lymphovascular invasion (p=0.006), distant metastasis (p=0.049), high Ki67 expression (p=0.000) and K-ras expression (p=0.002). The Kaplan-Meier analysis revealed a shorter period of survival with p63 over-expression (p less than 0.001). The Cox-regression model analysis showed that p63 over-expression was an independent prognostic marker in CRC (p=0.000).

Conclusion: P63 expression was increased from normal to adenoma to carcinoma sequence. Moreover, p63 cytoplasmic expression seems to be related to high Ki67 indexing, K-ras expression, advanced tumor stage and poor clinical outcome of CRC. These findings suggest a significant role of cytoplasmic p63 expression in tumor progression and prognosis.