%0 Journal Article %A S Tangjitgamol %A S Srijaipracharoen %T EP627 Clinico-pathological aspects of vanishing endometrial cancer %D 2019 %R 10.1136/ijgc-2019-ESGO.684 %J International Journal of Gynecologic Cancer %P A367-A368 %V 29 %N Suppl 4 %X Introduction/Background The disappearance of cancer after an initial diagnosis without any definite treatment, particularly without any evidence of disease elsewhere, would be unexpected, so called ‘vanishing carcinoma’. This study aimed to assess the prevalence of vanishing endometrial cancer (EMC) in our institution which is a tertiary hospital for cancer care during the 20-year period. The clinico-pathologic features of the patients including pre-operative findings, adjuvant treatment, and clinical outcomes were also studied.Methodology Patients who had pre-operative tissue diagnosis of EMC, and had surgical treatment including hysterectomy in the institution between 1995 and 2015 were identified. The patients who had no residual carcinoma in all pathologic specimens including the uterus were included. Pre-and post-operative clinico-pathological data were collected. Clinical outcomes including recurrence and survival of the patients were studied.Results Among 422 patients who had tissue diagnosis of endometrial cancer, twenty patients had no residual cancer in the hysterectomy specimens. Three patients who had pre-operative radiation therapy or had evidence of endometrial cancer outside the uterus, so 17 patients (3.8%) were diagnosed as having vanishing cancer. One of the 17 patients, who had pre-operative endometrioid endometrial cancer, had adjuvant chemotherapy for synchronous serous carcinoma of fallopian tube. From a follow-up period of 62.7 months (range, 6.8–184.4 months), no recurrences were found. Only 2 patients were dead of other diseases.Conclusion The prevalence of vanishing endometrial cancer was 3.8%. Patients with vanishing endometrial cancer had excellent prognosis. Adjuvant treatment may not be needed. However, periodic surveillance was still recommended because data were derived from only small number of patients.Disclosure Nothing to disclose. %U https://ijgc.bmj.com/content/ijgc/29/Suppl_4/A367.2.full.pdf