Introduction Serous endometrial intraepithelial carcinoma is described as a malignant, superficial spreading lesion with risk of extrauterine spread at time of diagnosis and poor outcome. The main objective of this study was to evaluate the surgical management of patients with serous endometrial intraepithelial carcinoma and its impact on oncologic outcomes and complications.

Methods This Dutch observational retrospective cohort study evaluated all patients diagnosed with pure serous endometrial intraepithelial carcinoma in The Netherlands, from January 2012 to July 2020. The pathological examination was reviewed by two pathologists with expertise in gynecological oncology. Clinical data were obtained when the diagnosis was confirmed. Primary outcome is progression free survival, secondary outcomes are duration of follow-up, adverse events related to surgery and overall survival.

Results A total of 23 patients from 13 medical centers were included, of whom 15 (65.2%) presented with postmenopausal blood loss. In 17 patients (73.9%) the intraepithelial lesion was present in an endometrial polyp. All patients underwent hysterectomy of whom 12 patients (52.2%) were surgically staged. None of the staged patients showed extrauterine disease. Two patients received adjuvant brachytherapy. There were no recurrences of disease (median follow-up duration of 35.6 months (range; 1.0–108.6) and there were no disease-related deaths in this cohort.

Conclusion/Implications In patients with serous endometrial intraepithelial carcinoma median progression free survival reached nearly three years and no recurrences have been reported. Our results do not endorse the WHO 2014 advice to treat serous endometrial intraepithelial carcinoma as high grade, high risk endometrial carcinoma. Full surgical staging might possibly lead to overtreatment.