OC16.03: Fertility‐sparing surgery and borderline ovarian tumours: oncological and fertility outcomes from a UK London gynecological oncology centre

To determine the oncological and fertility outcomes following Fertility Sparing Surgery (FSS) for the management of Borderline Ovarian Tumours (BOTs). A retrospective cohort of 172 women who underwent surgical management of BOTs between January 2004 and December 2020. Three histopathological subtypes of BOT were diagnosed: 120 (69.8%) serous, 43 (25%) mucinous and 9 (5.2%) seromucinous. The mean age of presentation was 44.8, 38.9 and 38.8 years respectively. 52.3% (90/172) underwent FSS, 45.3% (78/172) non- FSS and 2.3% (4/172) unknown. Within the serous group the recurrence rate amongst women who underwent FSS was 36.8% (21/57), on average 51.1 months post- operatively (SD ± 35.0); compared to 9.5% (6/63) amongst women who underwent non-FSS. All recurrences in the latter group presented as progression to low grade serous ovarian cancer, on average 62.2 months (SD ± 48.9) post-operatively. Two recurrences of BOTs occurred in the seromucinous group following FSS. Within the serous group, a significant difference between type of surgery performed (FSS v Non-FSS) and association with recurrence of BOT was observed (Pearson Chi- Square: p = 0.000; x2=20.613, 95% CI (0.126-0.427). The survival rate was 100%. US guided laparoscopic ovarian wedge resection was introduced as a novel method of FSS in 12 women, of which there were no surgical complications. Type of FSS was not significantly associated with recurrence of BOT. (Pearson Chi- Square x2=3.166, p = 0.379). Pregnancy rate per woman of reproductive age was 32.4% (22/68), 25.8% (8/31) and 42.9% (3/7) and successful livebirth rate per pregnancy was 75.7% (28/37), 46.7% (7/15) and 66.7% (2/3) in the three groups respectively. Type of FSS is not associated with recurrence of BOT. Successful oncological outcomes are observed from ultrasound guided laparoscopic ovarian wedge resection. Spontaneous pregnancies can be achieved during interval monitoring of disease following FSS.