الفهرس 
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Abstract
Colorectal cancer (CRC) is one of the most common forms of human cancer worldwide with approximately 1 million new cases detected every year (Parkin et al., 2005). Early detection, adequate surgical excision and optimal adjuvant treatment are of critical importance if a favorable outcome is to be achieved.
The expression of SATB2 protein is primarily preserved in cancer cells of colorectal origin, indicating that SATB2 could function as a clinically useful diagnostic marker to distinguish colorectal cancer (CRC) from other types of cancer. SATB2 is highly sensitive and specific when used in combination with CK20 to detect colonic origin in lymph node as well as distant metastasis (Magnusson et al., 2011).
The KRAS mutations are key mediators in EGFR signaling pathway play a crucial role in the colorectal pathogenesis and are associated with prognosis of colorectal carcinoma (Larki et al., 2017).
The aim of this study was to further explore and validate the specific expression pattern of SATB2, CK20 and KRAS and correlation of the results with clinicopathological parameters and prognosis also to detect colonic origin in metastatic lymph nodes and distant metastasis of unknown primary.
SATB2, CK20 and KRAS expression was examined by the immunohistochemistry in a series of 30 cases of colorectal carcinoma, 20 cases of lymph node metastasis and 10 distant metastasis cases of unknown primary. Results were correlated with several clinicopathological parameters including age at time of diagnosis, gender, tumor size, histopathological type/grade, clinical stage, lympho-vascular invasion, tumor location and recurrence status.
Both SATB2 and KRAS expression were significantly higher in older age cases (p =0.03, and 0.0099 respectively), their expression showed a significant correlation with distant lymph node metastasis (group II) (p=0.002 and 0.0003 respectively), while it showed no significant correlation with tumor clinical stage (p=0.9 and 0.95 respectively) and tumor grade (p=0.36 and 0.714 respectively).
When assessing tumor local recurrence relation with KRAS expression, there was a significant correlation (p=0.001).
CK20 expression showed neither significant correlation with tumor clinical stage (p=0.69) nor lymph node metastasis (p=0.37).
The three markers (SATB2, CK20 and KRAS) showed positivity (9 cases for SATB2, 8 cases for CK20 and 6 cases for KRAS) in distant metastasis cases from unknown primary in liver, omentum and ovary and proved that they were of colorectal origin.
Chapter (6): Summary, Conclusion and Recommendations
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6.2 Conclusion
The specific expression of SATB2 in a large majority of colorectal carcinoma
SATB2 is a sensitive and highly specific marker for colorectal carcinoma especially when used in combination with CK20.
SATB2 can be used as a complementary tool for differential diagnosis of carcinomas of unknown primary origin.
KRAS protein expression might be associated with disease aggressiveness and it could be a useful prognostic marker in colorectal carcinomas.
6.3 Recommendations
Studying the expression of SATB2 and CK20 in combination on a large scale with inclusion of more lymph node and distant metastasis cases to confirm the present results and ascertain their role in diagnosis of carcinomas of unknown primary.
Further studies with adequate follow up are recommended to assess the relation between KRAS expression and colorectal cancer recurrence.
Further exploration of prognostic potential of KRAS to evaluate whether it should be included in routine immune panels as additional support for oncologists in determining therapeutic choices for the patients.