الفهرس 
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Abstract
Colorectal cancer affects over a million people annually worldwide, and 5 year mortality is nearly 50% with this disease. Although screening programs may have some effect on reducing CRC-related mortality, improved patient staging and individualized treatment selection based on biomarkers can theoretically improve treatment efficacy and impact favourably CRC-related mortality.
P27kip1 is a nuclear member of the kip/cip family of cyclin dependent kinase inhibitors and is a negative cell cycle regulator that is thought to play a rule in tumour suppression. Reduced levels of p27kip1 are frequent in human cancers and these have been associated with poor prognosis.
The objective of this study is to assess the expression of p27 in colorectal carcinoma and to analyze the possible association between p27 immunostaining and other clinicopathological parameters.
The material of this study consisted of 40 cases of previously diagnosed colorectal carcinoma obtained from archives of Pathology department, Faculty of Medicine, Cairo University during the period from May 2014 to May 2015. The paraffin blocks were recut at 5 microns thickness and stained with hematoxylin & eosin and p27 monoclonal antibody.
Demographic data including age and sex were obtained from the hospital charts. The age incidence ranged from 26 years up to 85 years with an overall mean age 58.4 years and peak incidence among the age group 40-60 years. The male to female ratio was 1.6: 1.
Regarding tumour location, 70% of the studied tumours were located in the colon while 30% were located in the rectum. Among the studied colonic tumours the left colon was the most frequent location representing 27.5% of total studied cases. Most of the studied tumours were ≥5 cm in their largest diameter (85%) whereas 15% of cases were <5 cm.
In this study, Adenocarcinoma was the most frequent histological type representing 80% of the total studied cases followed by mucinous adenocarcinoma (12.5%) and signet ring carcinoma (7.5%). Grade II tumours were the most frequent representing 75% of the total studied cases followed by grade III (20%) and grade I (5%). According to the depth of tumour invasion (T stage), T3 tumours represented 65% of the cases, T4 tumours (22.5%) and T2 tumours (12.5%). Lymph node metastases were observed in 40% of the studied cases.
In the studied tissue sections, p27 nuclear immunoreactivity was observed in 45% of cases while 55% were negative for p27 expression. Low expression of p27 was found to be correlated significantly with high grade and more aggressive tumours (P value= 0.046). There were also a significant inverse correlation between the expression of p27 and the depth of tumour invasion (P value= 0.006). Furthermore, reduced levels of p27 expression were significantly observed in tumours with lymph node metastases than in tumours with free lymph nodes (P value= 0.043).
The correlation between p27 expression and other clinicopathological parameters such as age, sex, tumour size, tumour location and tumour histologic type was statistically insignificant.