Evaluation of the immunohistochemical expression of p16 in colorectal carcinoma and correlate its expression to different clinical and pathological parameters as patients' ages, sexes, tumor location, histopathological phenotype, status of nodal involvement, perineural and lymphovascular invasion.

Colorectal Carcinoma is very common nowadays, with increasing need for further research.

p16 is tumor suppressor gene with a vital rule ; inactivation of p16 leads to tumor formation and progression.

50 Specimens will be collected from Pathology Department of Sohag University Hospital. Sufficient clinical and histopathological data will be attached for each case.

The previously processed formalin-fixed, paraffin-embedded tissue blocks will be used to get Hematoxylin & Eosin stained sections to confirm the diagnosis and to detect the histopathological type, grade and stage of each tumor.

Another sliced tissue sections will be immunohistochemically stained with p16 monoclonal antibodies to be evaluated with the positivity, intensity and distribution of the detected stain.

Inclusion Criteria:

1. Specimens from patients with colorectal cancer.
2. Tissue blocks with sufficient material.
3. Specimens with sufficient clinical data.

Exclusion Criteria:

1. Tissue blocks with insufficient, destroyed or necrotic material.
2. Specimens with insufficient clinical data.

Fifty (50) cases of colorectal cancer will be performed from archieved formalin-fixed, paraffin-embedded tissue blocks referred to Pathology Department, Sohag University Hospitals.

Not decided yet