Introduction/Background Treatment in high-grade serous ovarian cancer (HGSOC) depends upon knowledge of BRCA and homologous recombination deficiency (HRD) status. Hence, tumor quality is critical for successful genomic analyses. We investigated if samples from ultrasound-guided biopsies (UGB) could yield conclusive results compared to surgical excision specimens (SES).

Methodology A retrospective analysis of HGSOC confirmed through UBG was done. Paired temporal cases from SES were selected. BRCA and HRD analysis was done with Ion GeneStudioTM S5 Prime System using the Oncomine BRCA assay and Oncoscan CNV array (Thermo Fisher Scientific).

Results 78 patients diagnosed with HGSOC between 2021–2023 were included. 113 genomic analyses were performed (32 sBRCA and 10 HRD from UBG; 44 sBRCA and 27 HRD from SES). sBRCA analysis from UGB was successful in 65% of samples. Cases with successful results had a higher number of tumor samples (mean 5.5 vs. 4.9), higher total tumor length (mean 19.5 vs. 16.6 mm), higher DNA quality (mean 15.5 vs 1.5 ng/μλ) and significantly lower number of IHC stains/series (mean 6.3 vs. 8.4, p=0.024; mean 1.2 vs. 1.8, p=0.06) in comparison with unsuccessful results. Adnexal and omental biopsies were significantly associated with a lower rate of conclusive results than other (cytoblock, colon, lymph node, peritoneal/pleural nodule) sites (50% vs 85%, p=0.034). In addition, UGB done on Friday had a lower rate of successful results than biopsies performed Monday-Thursday (42.8% vs. 69.5%). HRD analysis from UGB was successful in 60% of samples. sBRCA and HRD analysis from SES was successful in 88% and 96% of samples and there were no differences regarding the timing of surgery or NACT.

Conclusion Careful planning of UGB and stepwise tissue diagnosis with respect to influencing factors can increase the success rate of genomic analyses in HGSOC and could be a feasible alternative to SES.

Disclosures PK received support from AstraZeneca, Roche, Sandoz, BMS, MSD. AP received support from AstraZeneca, BMS, MSD, Roche, Sandoz, Ipsen, Lilly.