DETECTION OF OVARIAN-CANCER CELLS - COMPARISON OF A TELOMERASE ASSAY AND CYTOLOGIC EXAMINATION

Telomerase is an enzyme essential for the normal replication of chromo somes, Telomerase activity is absent in most somatic cells in adults, but it is usually expressed in cancer cells, including ovarian carcino ma cells, Our principal goal was to compare the sensitivity of a telom erase assay, i,e,, the telomeric repeat amplification protocol (TRAP) assay, with that of cytologic examination in detecting cancer cells in the peritoneal cavity of patients with ovarian carcinoma, Methods: TR AP assays and cytologic examinations were performed on peritoneal wash ings and ascitic fluids from 42 patients with active ovarian carcinoma , Control specimens included washings from 29 patients with benign ova rian diseases and ascitic fluids from 14 patients with liver failure, We also evaluated the stability of telomerase in ascitic fluids left u nprocessed at room temperature as well as the ability of the TRAP assa y to detect cancer cells in mixtures containing large numbers of norma l cells, Results: Specimens from 37 (88%) of the 42 patients with ovar ian carcinoma tested positive for telomerase, Cytologic examination de tected cancer cells in only 27 of the telomerase-positive specimens (i ,e,, in specimens from 64% of the 42 patients), This difference of 24% (95% confidence interval = 17%-30 %) in sensitivity between the two t ests was statistically significant (two-sided P =.002), Specimens from five of the patients with ovarian carcinoma were cytologically negati ve and telomerase negative, All 43 control specimens were cytologicall y negative, but the TRAP assay detected telomerase in two of them, Tel omerase activity was detected in unprocessed samples left at room temp erature for 5 days and in mixtures containing a small number of cancer cells and a 2000-to 10000-fold excess of normal cells, Conclusions: A ssaying for telomerase is more sensitive than cytologic examination in detecting cancer cells in the peritoneal cavity of patients with ovar ian carcinoma.