الفهرس 
ANATOMY OF THE COLONOnly 14 pages are availabe for public view
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Abstract
CRC in Egypt is commonly diagnosed in elder people with a mean age about 53 years old, which is a decade younger than the corresponding age in the USA. Most of the cases of CRC in young age in Egypt present with more advanced stages and carries an aggressive behavior regarding the histopathological cell types and grades with poor survival rates (12). The current study has showed an increased incidence of post-resection positive cytology in young age than patients in older age group.
In the current study, intra-peritoneal exfoliated cancer cells were examined in patients with colorectal cancer by intraoperative lavage cytology pre and post tumor resection. The Conventional cytology is the most popular method because it is relatively inexpensive and requires neither the preservation of RNA nor the implementation of a complex technique (113). The specificity and/or sensitivity of positive tumor cells in peritoneal lavage fluid revealed specificity ranged from 83% up to 100% (55,104), and sensitivity of 86% (115).
The rate of positive cytology in peritoneal fluid lavage detected by this study was 12 % and from previous studies ranged from 2.1% to 52% in patients with colorectal cancer and positive cytology (100, 134). This discrepancy in rates of detection of positive cytology can be explained by the heterogeneity of the techniques used to detect malignant cells in peritoneal lavage fluid (100, 116).
The rate of positive pre-resection lavage was 8% in current study and the incidence reported from previous studies ranged from 3.7 to 13.3% (100, 134,135). The presence of malignant cells in the pre-resection washings may be due to the fact that the tumor had invaded through the full thickness of the bowel wall and involved the serosa.
Positive post-resection lavage for originally negative pre-resection cytology was 4.4% in this study and 13.3 to 26.7% in previous study (135).
The origin of malignant cells in patients with only post-resection positive washings is less certain. The source of these tumor cells may include severed lymphatic vessels, disrupted tissue interstices at the lateral margins of tumor dissection, venous blood that is heavily contaminated with tumor cells or cancer cell spillage by surgical manipulation (134).
These findings are matched with the results of the current study as results of that
has shown that there was a statistically significant prevalence of positive cytology (either pre or post resection) in case of positive lymph nodal metastases.
One of the significant factors that affect the prognosis of colorectal cancer is the pathologic TNM stage, especially T-status. It has been documented by similar studies that the more advanced stages of disease, i.e. the depth of bowel wall invasion (pT3/4), the higher the incidence of tumor-positive peritoneal lavage (49,72). The current study showed that the majority of patients with positive pre-resection cytology were T3 75%, while T2 were present in 25%. Moreover, patients who had pre-resection negative cytology who converted to positive post-resection cytology were only T3/T4. However, the difference could not reach a statistically significant power. This can be attributed to small number of included cases.
Studies have shown that the incidence of malignant cells in peritoneal lavage before tumor resection was higher in colon cancer than rectal cancer. Authors of these studies have attributed this to the fact that organs which have peritoneal fluid resorption
Discussion
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(omentum and omental appendages) have a high incidence of implants as well as the ileocecal area, which is fixed to the retroperitoneum (56). In the current study tumor location did not show significant impact on the detection of positive pre-resection cytology. However, positive post-resection cytology in cases of negative pre-resection one was significantly more prevalent in cases of rectal cancer. This could be explained by inclusion of originally extra-peritoneal rectal tumor into the peritoneal cavity during resection, hence, more liability for tumor cell spillage within the surgically opened peritoneal space.
Studies have documented that mucinous subtype of CRC is associated with a higher incidence of free IPCC (62, 66, 67). This finding matches of the results of the current study that revealed that patients with the mucinous histologic variant of colorectal cancer were significantly associated with higher incidence of free IPCC in the pre-resection cytology. This can be attributed to that this tumor variant tends to have higher ratio of lymph node infiltration (66, 67). Moreover, mucinous CRC are more frequently diagnosed when they are already in advanced stages especially in younger patients. This explains their preferential tendency to metastasize to peritoneum (62).
Adding to the existing facts, the use of lavage cytology, along with other prognostic factors, will identify high risk patients for recurrence like positive lymph nodes for malignancy or mucinous carcinoma and for further management, even after curative surgery. Moreover, the site of cancer infiltration of the serosa should be covered during the operation to prevent the exfoliation of tumor cells, and it is also necessary to exercise care to prevent injury to the bowel by surgical manipulations.