Abstract
Cytology from gastrointestinal (GI) cancers is frequently obtained from ascites and peritoneal washing fluids. Examination of ascites and peritoneal washing fluids from patients with GI cancers can help in the tumor staging and prognosis. Tumor-derived DNA in these cytology samples can be a target for next generation sequencing (NGS). Targeted NGS was evaluated in ascites and peritoneal washing samples obtained from 33 patients with GI cancers. These sequences were compared with those from tumor tissue samples, and correlated with cytopathologic findings of the ascites and peritoneal fluid samples. The correlation between fluid and tissue genotyping results was 25%, with a sensitivity of 21.43%. The volume of tumor contained within the fluid samples was low, ranging from ~0 to 10%. Importantly, the sensitivity of detection of somatic mutations in the fluid samples could be increased to 69.2% by assessing samples containing >2% tumor volume. Evaluation of cells from ascitic fluid showed the presence of KRAS, TP53, and CDH1 mutations in 33, 13, and 7%, respectively, of patients with pancreatic cancer, and the presence of KRAS, TP53, and APC mutations in 25, 12, and 13%, respectively, of patients with gastric cancer. Ascites of one of the latter patients acquired KRAS mutation, which was a novel mutation during metastasis. Targeted NGS of ascites and peritoneal washing fluid have clinical implications, as well as limitations, in patients with GI cancers. NGS-based cytology examination may expand cytomolecular practices in GI cancer patients.
Highlights
Cytology specimens for diagnostic purposes can be obtained by exfoliation or aspiration of cells from cancer patients
Ascitic fluid was obtained from 13 patients with pancreatic cancer, eight with gastric cancer, and six with non-malignant diseases; whereas, peritoneal washing fluid samples were obtained from six patients with gastric cancer
Ascites samples were obtained from 13 patients with pancreatic cancer, eight with gastric cancer, and six with non-malignant diseases, and peritoneal washing samples were obtained from six patients with gastric cancer
Summary
Cytology specimens for diagnostic purposes can be obtained by exfoliation or aspiration of cells from cancer patients. Ascites and peritoneal washing fluids are common sources of cell specimens from gastrointestinal (GI) cancer patients [1, 2]. Cytologic evaluation of ascitic fluid can Targeted Sequencing of Peritoneal Fluid identify the presence of malignant cells and rule out benign causes. Peritoneal washing fluid is obtained by irrigation of the peritoneal cavity with normal saline solution. Cytologic evaluation of peritoneal washing fluid can detect occult cancer cells in GI cancer patients, even without the collection of ascitic fluid. Peritoneal metastasis is the most common pattern of recurrence and cause of death in patients with cancers of the GI tract, making cytologic evaluation of peritoneal washing fluid important in determining cancer stage and predicting recurrence in these patients
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