Introduction/Background Ovarian tumors are rare during pregnancy and are observed in 2.3–8.8% of pregnant women. However, most of them are benign in nature, and only 1–6 % are reported to be malignant.

Methodology The material of the study was the data of patients extracted from the Belarusian Cancer Registry for the period 2015–2022, who applied for a consultation to the our Cancer Center. The course and outcomes of treatment, the relationship with the method of delivery and the extent of surgical intervention were retrospectively analyzed.

Results Of the 20 pregnant women, complete data were available in 10 patients. The median patients` age was 29 years (range 21–38 years). The median gestational age at ovarian tumor diagnoses was 20.5 weeks (range 5–36 weeks). Tumors were classified as stage IA in 6 patients, IB – in 1, IC – in 2, and IIB – in 1.

All patients underwent surgical treatment Conservative approach was used in 2 cases, fertility-sparing surgery with comprehensive staging operation in 8 patients. The complete staging procedure included careful exploration, peritoneal cytology, random peritoneal biopsies, omentectomy, appendectomy (in mutinous tumors).

Morphologically, 5 patients were diagnosed with epithelial borderline tumors (serous, mucinous), 1 – epithelial ovarian cancer, 4 - non-epithelial malignant tumors.

The median gestational age at delivery was 39 weeks (range 36–42 weeks). All women underwent caesarean section without complications. Three patients (IC, n=2; IIB, n=1) received adjuvant chemotherapy.

With a median follow-up of 46.95 months (4.3–89.6 months), all patients are alive without signs of disease.

Conclusion In our study, all surgical interventions in patients with ovarian tumors during pregnancy were conservative or fertility sparing, did not affect the course and outcomes of pregnancy and oncological results. The interdisciplinary collaboration of specialists in perinatal medicine, gynecological oncology, chemotherapy, neonatology and psychology appears to be crucial to achieve the best possible maternal, neonatal and oncological outcomes.

Disclosures Authors have no any disclosures