A Study of Immunohistochemical Expression of p63 in Colorectal Carcinoma

A key player in the development of colorectal carcinoma is p63, a protein belonging to the p53 family. Tumorigenesis, invasion and metastasis are linked to its elevated expression in certain malignancies.

In this study, we aimed to investigate the immunohistochemical expression of p63 in colorectal carcinoma along with its correlation to clinicopathological parameters and its precursor lesion colorectal adenoma.

This study used 49 formalin-fixed paraffin-embedded tissue sections: 16 surgically resected (14 carcinomas and 2 adenomas) and 33 colonoscopy biopsies (28 carcinomas and 5 adenomas). Tumour characteristics (size and location) and demographic data (age and sex) were obtained from the archive system. Haematoxylin- and eosin-stained sections were reassessed for histological grade, subtype, lymphovascular invasion, invasion depth, lymph nodes and metastasis. Statistical analysis was performed with Fisher's exact test, Microsoft Excel and SPSS Version 21. H-Score was used for immunohistochemistry.

P63 expression was absent in normal mucosa, while P63 immunohistochemistry was positive in 43 (88%) cases. Forty-two (86%) out of 49 cases showed cytoplasmic expression of p63, of which 35 cases (83.3%) were carcinomas. P63 expression revealed a significant correlation with histological subtype (P < 0.001), histological grade (P < 0.001), distant metastasis (P = 0.033), tumour, node and metastasis/American Joint Committee on Cancer (TNM/AJCC) stage (P = 0.049) and between colorectal carcinoma and adenoma (P < 0.001).

Moderate-to-strong cytoplasmic p63 expression was seen only in malignancy, suggesting its role in carcinogenesis. Increased p63 staining intensity from low- to high-grade tumours indicates p63 as a marker of poor differentiation. The correlation between metastasis and stronger p63 expression with higher TNM/AJCC stages confirms elevated p63 in aggressive tumours.