Molecular alterations in Homologous Recombination Repair (HRR) genes have been associated with clinical benefit from chemotherapy and/or Poly (ADP-ribose) polymerase (PARP) inhibitors in patients with epithelial ovarian cancer. Therefore, the performance of tumor molecular profiling is currently recommended by international guidelines at initial diagnosis, among other reasons, for the modification of the treatment plan. The investigators' hypothesis was that tumor molecular profiling reveals additional parameters that can improve the predictive and prognostic role of the mere presence of HRR gene mutations. The study aimed to investigate the prognostic and predictive role of clonality of pathogenic variants in HRR genes and/or concurrent pathogenic variants in other clinically relevant genes.

Inclusion Criteria:

• Diagnosed with epithelial ovarian cancer
• Received treatment at HeCOG-affiliated institutions
• Have signed informed consent
• With adequate tumor tissue for analysis

Patients with epithelial ovarian adenocarcinoma with archival tumor tissue available for analysis were identified through the Hellenic Cooperative Oncology Group (HeCOG)'s tumor repository. Patients had received treatment at HeCOG-affiliated institutions from following standard international guidelines.

In total, 501 patients with ovarian adenocarcinoma were included in the study (median age at ovarian cancer diagnosis was 58 years). Tumor histological types included predominantly high-grade serous, followed by endometrioid and clear cell carcinomas. All except 3 patients underwent surgery at initial diagnosis, most commonly total abdominal hysterectomy with bilateral salpingo-oophorectomy.