RT Journal Article SR Electronic T1 EP1045 Differences of tumour behaviour among various types of epithelial ovarian cancer JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A553 OP A553 DO 10.1136/ijgc-2019-ESGO.1088 VO 29 IS Suppl 4 A1 陳, 昱 A1 Lin, H YR 2019 UL http://ijgc.bmj.com/content/29/Suppl_4/A553.1.abstract AB Introduction/Background Epithelial ovarian cancer (EOC) consisted of several histologic types, including serous, mucinous (MC), clear cell, endometrioid carcinoma (EC), etc. Few studies evaluated the rare histologic types, such as seromucinous carcinoma (SMC) and mixed-type carcinoma (MTC). The aims of present study were to investigate the clinical characteristics and outcomes of this uncommon histology and to compare with other types of EOC.Methodology A total of 414 EOC patients of various histologic types between Jan. 2008 and Dec. 2016 were included for analysis. The clinical and pathological characteristics of SMC and MTC were compared with other common histologic types. Chi-square test was used for analysis of distribution of category variables. Kaplan-Meier method and Cox regression were used for analysis of survival outcomes.Results SMC and MTC comprised 1.2% and 4.6% of all epithelial cell types in our series, respectively. The mean age of diagnosis of both was 52.8 years old which was older than other EOC (51.2 years old). Most SMC was diagnosed at early stage (I, II, 80%), while the stage of MTC was equally distributed. MTC (9.6 cm) and SMC (8.9 cm) had bigger mean size than high-grade serous carcinoma (HGSC, 7.1 cm), but much smaller than MC (14.9 cm). MTC predominantly occurred unilaterally (70.6%). SMC and MTC were associated with endometriosis, especially SMC (60%). With a median follow up of 43 months, 5-year progression free/ overall survival rate of SMC and MYC were 60.0%/60.0% and 64.7%/81.3%, respectively. The survival rate of SMC and MTC were worse than EC, similar to MC, but better than HGSC.Conclusion SMC and MTC possess relatively special clinicopathologic features, including age, size, bilaterality and component of endometriosis. But there are no significant differences in survival outcomes among SMC and MTC, and EC.Disclosure Nothing to disclose