Advantages of assaying telomerase activity in ascites for diagnosis of digestive tract malignancies

AIM: To evaluate the diagnostic value of assaying telomerase activity in ascites cells for the differential diagnosis of malignant and non-malignant ascites. METHODS: Ascites from 40 patients with hepatocellular carcinoma (HCC), 31 with non-HCC gastrointestinal carcinoma (CA), and 24 with liver cirrhosis (LC) were analyzed for telomerase activity. The telomerase activities in cell pellets from ascites were measured according to the Telomeric Repeat Amplification Protocol (TRAP) and quantified with a densitometer. RESULTS: Positive telomerase activity was detected in 16 of 31 (52%) CA patients, 10 of 40 (25%) HCC patients, and 1 of 24 (4%) LC patients (P<0.001). The telomerase activity was higher in the ascites of CA patients than in the ascites of HCC or LC patients (CA: 22.9 +/- 5.8, HCC: 6.7 +/- 2.5, LC: 1.3 +/- 1.3, P = 0.001). Cytology was positive in 18 CA patients (58%) and 1 HCC patient (2.5%), respectively. The positive telomerase activity was not related to patients' age, gender, and ascitic protein concentration, but to white blood count (r = 0.31, P = 0.002), neutrophil count (r = 0.29, P = 0.005), and the C-reactive protein level (r = 0.29, P = 0.018). When the results of both cytological examination and telomerase assay were considered together, the sensitivity increased to 77% for CA patients, 25% for HCC patients, and 48% for all 71 gastrointestinal cancer patients. CONCLUSION: Combining cytological examination of ascites with telomerase activity assay significantly improves the differential diagnosis between malignant and non-malignant ascites.