الفهرس 
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Abstract
Colorectal cancers, among other neoplasms are in the third place in morbidity and mortality after the breast and lung cancers in women and prostate and lung cancers in men. Colorectal cancer is also the third cause of death among all neoplasmal diseases. The incidence of this disease has been rising especially in developed countries. The survival rate after radical operative treatment and chemo- or radiotherapy is still unsatisfactory. The 5-year survival after radical treatment was about 60% in the Unites States and Western Europe, whereas it was only about 40% in Eastern Europe. The recurrence of the disease is dependent on the progression of neoplasmal metastases to lymph nodules and distal organs and is the most common cause of death.
The routine examinations of specimens with the estimation of the histopathological grade of malignancy, clinical evaluation and even the changes in CEA, CA19.9 levels in the serum evaluation all still have limited ability and require serial measurements to identify patients with colorectal cancer.
Therefore, there is a desperate need for an early and sensitive marker for detection of colorectal cancer in order to interfere early and thus improve the prognosis. A candidate marker for detection of colorectal cancer is CD44.
CD44 described at first by Dalchau in 1980 is a cell surface transmembrane glycoprotein which occurs in both healthy and neoplasm cells. The gene which codes for CD44 consists of 20 exons, and 10 of them can be combined, so there are a lot of its variants. It can also be modified just after the process of translation. The most common molecule with a molecular weight 85-90 kd is called standard molecule.
CD44 is the main surface receptor of hyaluronic acid. It participates in many cellular processes, including growth, survival, differentiation, and motility. It is a unique adhesion molecule and plays a role in cancer cell migration and matrix adhesion in response to a cellular microenvironment, thus enhancing cellular aggregation and tumor cell growth.
It is speculated that CD44 has a function in cancer expansion and invasiveness and the elucidation of CD44 function in different cancer conditions is an important objective of future studies. It was previously included in several studies on patients with primary or metastatic carcinoma of the colon, rectum, stomach, liver, lung, nasopharynx, ovary, breast, glioblastoma, kidney, prostate, melanoma, as well as hematological malignancy as chronic myeloid leukemia and non Hodgkin lymphoma,
In this regard, our study aimed to evaluate the clinical utility of serum CD44v6 in comparison to CEA and CA19.9 in patients with colorectal cancer. Our study was conducted on 50 patients who presented to the oncology unit of Ain Shams University Hospitals. The patients’ group included group I (20 patients with primary colorectal cancer) and group II (30 patients with metastatic colorectal cancer). In addition, 20 healthy subjects were included as controls.
All patients included in this study were subjected to full medical history taking, clinical examination, routine investigations including complete blood picture, liver function tests, pelvi- abdominal ultrasound and postoperative histopathological examination of the tumors. In addition, CD44v6 was measured by ELISA in both patients and control subjects. CEA and CA19.9 were measured by electrochemiluminescence immunoassay in the same groups.
Serum levels of CD44v6, CEA and CA19.9 were significantly higher in group I and group II compared to control group.
No significant difference was found between group I and group II as regards serum levels of CEA, CA19.9 and CD44v6.
Our correlation study between CD44v6 and different studied parameters revealed a significant positive correlation between CD44v6, CEA and CA19.9 in studied groups.
A significant positive correlation was also found between CD44v6 and age. On the other hand there was no significant correlation between it and tumor size.
Statistical comparison between the levels of CEA, CA19.9 and CD44v6 among different stages of lymph node metastasis reveals no statistically significant difference.
There was no statistically significant difference in CD44v6 levels among different grades of tumor invasion.
There was no statistically significant difference in CD44v6 levels among patients with organ metastasis and those without organ metastasis.
There was no statistically significant difference in CD44v6 levels between patients with Dukes’ stages C and D.
Regarding the sensitivity and specificity of CD44v6, at a cut-off value 250 ng/mL, the diagnostic sensitivity, specificity, positive predictive value, negative predictive value and efficiency were 98%, 100%, 100% and 95.2% respectively.