Efficacy of a liquid-based thin layer method for cervical cancer screening in a population with a low incidence of...

The performance of the ThinPrep(R) Pap Testtrade mark (TP) (Cytyc Corp., Boxborough, MA) for detection of cervical cancer precursors in a population with a low incidence of disease was evaluated. This prospective trial compared results obtained with TP to those obtained with the standard cytologic smear in women from the general community who were being screened for cervical cancer from January 1, 1995-December 31, 1997 by physicians in private practice (n x 130, 381 conventional examinations and 39,864 TP examinations). In the TP series there was a significant increase in the proportion of "satisfactory" examinations (91.9% TP vs. 72.2% conventional) and positive diagnoses (5.5% TP vs 2.4% conventional, odds ratio x 2.21; 95% confidence interval (CI), 2.08-2.34). The likelihood of detecting a high-grade squamous intraepithelial lesion (HSIL) by TP was significantly greater than in controls (odds ratio x 1.86; 95% CI, 1.68-2.06). Detection of low-grade squamous intraepithelial lesions (LSIL), or atypical squamous cells of undetermined significance (ASCUS), was significantly greater in the TP series than in controls (LSIL odds ratio x 3.41; 95% CI, 3.07-3.79; ASCUS odds ratio x 1.68; 95% CI, 1.56-1.82). A histologic lesion was confirmed in 141 (93%) of the biopsies for HSIL (130 HSIL or greater, 10 LSIL, 1 SIL not otherwise specified). In conclusion, both diagnostic sensitivity and sample adequacy were significantly improved using the ThinPrep(R) Pap test under routine conditions in an outpatient population with a low incidence of cervical cancer.