Analysis of risk factors of positive peritoneal cytology in patients treated for gastric cancer – preliminary report
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Presence of free gastric cancer cells in the peritoneal cavity of patients who underwent surgical treatment for gastric cancer is a negative prognostic factor and caused rapid disease recurrence, manifested as peritoneal metastases. Positive peritoneal cytology despite lack of visible peritoneal metastases was regarded as M1 class in the TNM classification (7th edition) in 2010. The aim of the study was to analyze factors associated with positive peritoneal cytology and identify groups of patients in whom diagnostic laparoscopy plus peritoneal lavage in the diagnostic process could affect therapeutic decisions. Material and methods. The study enrolled patients with gastric cancer who underwent surgical treatment at the Department of Surgery, Wielkopolskie Oncology Center in Poznań. During the laparotomy, after opening of the peritoneal cavity, 200 ml of physiological saline at 37°C was administered in the tumor region. After this fluid was mixed, 100 ml of lavage fluid was collected. This fluid was subsequently spun many times to obtain sediment for cytology and immunohistochemistry investigation using anti-BerEp-4, CK 7/20, and B72.3. Results of peritoneal cytology were analyzed jointly with clinical factors – patient’s age, sex and pathology factors – tumor invasion, involvement of lymph nodes, histological grade, histological type according to Lauren and localization of the cancer in the stomach. Results. Analysis of the peritoneal fluid for presence of free cancer cells was done in 51 patients. Positive peritoneal cytology was found in 12 (23.5%) patients. In the group of patients with positive cytology, all patients had T3/T4 tumors and all were found to have lymph node metastases, while G3 cancer was found in 83.3% of patients. In patients with positive cytology, diffuse gastric cancer according to Lauren predominated (9 of 12 patients, 75%), while in patients with negative cytology – intestinal type (20 of 39 patients, 51.2%). In the group of patients with positive histology, the whole stomach was involved by the cancer process in 7 of 12 patients (58.3%), while in the group with negative histology, in 29 of 39 patients the tumor was located in the gastric body and prepyloric part (74.4%). Conclusions. Based on this study we can conclude that determinants of positive peritoneal cytology include: tumor stage T3/T4, N+, G3, cancer located in the whole stomach, diffuse histological type according to Lauren.
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