Prediction of histological types of endometrial cancer by endometrial cytology

Few studies have examined the accuracy of preoperative endometrial cytology in diagnosing low- and high-risk histology in women with endometrial cancer (EC). This single-institutional retrospective study compared the accuracy of endometrial cytology and biopsy in preoperatively predicting low-risk and high-risk histology of EC.Between January 2006 and March 2013, 198 women with EC were examined by endometrial cytology, endometrial biopsy and hysterectomy specimen in National Kyushu Cancer Center. Among these women, 110 had endometrial cytology samples available to compare with endometrial biopsy, and were enrolled in our study (mean age ± standard deviation: 59.57 ± 10.32 years). Single-use plastic endometrial suction curettes were used in 12 of the 110 cases and thin metallic curettes for the rest.For type 2 EC, which includes grade 3 endometrioid adenocarcinoma and non-endometrioid histology, biopsy was 67.6% sensitive (25/37) and 84.9% specific (62/73); whereas cytology was 70.3% sensitive (26/37) and 91.8% specific (67/73). Cytology precisely diagnosed only one of 14 cases of serous carcinoma, but it diagnosed 11 of the 14 cases as type 2 EC, and its accuracy in distinguishing EC types was not inferior to endometrial biopsy (10/14). For EC, 9.1% (10/110) were unevaluable using biopsy, significantly more than the 0% (0/110) by cytology (P = 0.002).Although preoperative prediction of serous carcinoma was difficult, endometrial cytology had a higher evaluable rate for EC types. Endometrial cytology may complement endometrial biopsy in preoperative women with EC.