Detection of endometrial adenocarcinoma with the ThinPrep Pap test

The ThinPrep Pap Test (Cytyc Corp., Boxborough, MA) was introduced in the Loyola University Medical Center (LUMC) Cytopathology Laboratory in March 1997. This study presents a 26-month retrospective review of the cervicovaginal specimens on all patients who had a cytologic diagnosis of adenocarcinoma either by conventional (CS) or ThinPrep (TP) methods. From March 1997 through May 1999, 16,139 conventional smears and 29,589 TP Pap tests were sent to the LUMC cytopathology laboratory. The three diagnostic glandular categories included: atypical glandular cells of undetermined significance (AGUS); suspicious for adenocarcinoma, endometrial adenocarcinoma, and adenocarcinoma; not otherwise specified (nos). Cytohistologic correlation was performed on all available cases. Since endometrial adenocarcinoma occurs most frequently in peri- and postmenopausal patients, the percentage of patients over the age of 50 was determined for each method; 4,669 (29%) of the women receiving a CS were age 50 or over and 6,839 (23%) of the women who received the TP Pap test were in this age group. Sixteen endometrial lesions were identified on cytology, one (adenocarcinoma) with the CS method and 15 (six AGUS; suspicious for adenocarcinoma, four endometrial adenocarcinomas, and five adenocarcinomas; nos) with the TP method. The one CS case had biopsy confirmation. Fourteen of the 15 TP cases (93%) were confirmed by biopsy; one (7%) case had no follow-up. The TP Pap test yielded a higher percentage of endometrial adenocarcinomas (0.05%) as compared to CS (0.01%). Traditionally, CS has not been a method for the early detection of endometrial glandular lesions. However, of the patients diagnosed as having an endometrial adenocarcinoma in this study, the TP Pap test contributed to an increase in the detection of these lesions as compared to CS. The age group for the two methods was comparable.