Positive Peritoneal Lavage Cytopathology: Prevalence and Relation to Clinico-Pathological Characteristics of Colonic Adenocarcinoma: A Cohort Study

Background: Positive peritoneal lavage cytopathology (PPLC) is an established poor prog­nostic factor in CRC that has been proven in many studies and was associated with an increase in peritoneal recurrence , overall recurrence and mortality. The incidence of PPLC among CRC patients varied in different studies between 2.1-52%. Similarly, different variables were reported to correlate with peritoneal lavage positivity in published studies. The aim of this trial was to study the prevalence of free intraperitoneal malignant cells at the time of radical resection of colon cancer and to assess its relation to different clinico-pathological characteristics.

Patients and methods: This cohort study was conducted at the gastrointestinal surgery unit, general surgery department and the emergency hospital at Tanta University during the period from January 2020 ending in December 2020. Forty patients with non-metastatic primary colonic carcinoma were included in the study. Peritoneal lavage fluid was collected before radical resection of the tumour. One hundred milliliters of warm normal saline solution was installed into the peritoneal cavity and at least 80 ml of the lavage fluid was collected for cytopathological examination. After preparation, the sample was stained with Haematoxylin and Eosin and examined under a light microscope by an experienced cytopathologist.

Results: Eighteen smears (45%) were found positive for malignant cells. Among variables tested, a positive correlation was found between PPLC and a low BMI (< 25 kg/m2), the histopathological tumour type, an advanced pT stage, a high lymph node ratio and an advanced overall TNM stage.

Conclusion: In non-metastatic AJCC stage II and III colon cancer, the prevalence of PPLC detected by conventional cytopathology was found to be 45%. A low BMI <25kg/m2 , the presence of intraperitoneal free fluid at the time of the operation , a high lymph node ratio, an advanced T stage, histopathological type and an advanced overall TNM stage correlated positively with PPLC.