High-grade serous ovarian cancer is typically diagnosed at an advanced stage and remains associated with poor long-term survival. Reliable biomarkers for predicting disease course and treatment response are still limited.

Circulating tumor cells (CTCs) are malignant cells that detach from the primary tumor and enter the bloodstream. Their presence has been associated with disease progression and prognosis in several malignancies, including ovarian cancer. However, data on the morphological characteristics, immunophenotype, and clinical relevance of CTCs in high-grade serous ovarian cancer remain limited.

The ASTRA study evaluates the number and characteristics of circulating tumor cells in peripheral blood samples obtained from patients with high-grade serous ovarian cancer. The study examines CTC count, presence of CTC clusters and megakaryocytes, and immunophenotypic marker expression, and explores associations between CTC findings and clinical parameters and outcomes.

Results from this study may contribute to improved understanding of circulating tumor cells in ovarian cancer and support the development of liquid biopsy approaches for prognostic assessment and disease monitoring.

This prospective, single-arm interventional diagnostic study evaluates circulating tumor cells (CTCs) in patients with high-grade serous ovarian cancer (HGSC). The study is designed to characterize the morphological and immunophenotypic features of CTCs and to assess their association with clinical and prognostic parameters.

Eligible participants include adult women with histologically confirmed high-grade serous ovarian cancer (FIGO stage III or IV) undergoing first-line platinum-based systemic therapy. As part of the study protocol, an additional 10 mL peripheral blood sample is collected prior to initiation of systemic therapy. In participants with detectable CTCs at baseline, a second additional 10 mL blood sample is collected before cycle 4 of systemic therapy to evaluate treatment-related changes in CTC count and characteristics.

Circulating tumor cells are isolated using the Parsortix size-based microfluidic system, which preserves cellular morphology. Isolated cells are processed into cytospin preparations and analyzed using cytology staining, immunocytochemistry, and immunofluorescence methods. CTCs are evaluated for number, presence of single cells and clusters, and expression of epithelial and mesenchymal markers. Megakaryocytes and other non-tumor cells are assessed to ensure accurate cell classification.

Clinical data, including tumor stage, laboratory parameters (e.g., CA125 and immune-inflammatory indices), treatment information, and outcome data, are obtained from medical records. Progression-free survival and overall survival are assessed using clinical follow-up data and the national cancer registry.

Statistical analyses include descriptive statistics, correlation analyses between CTC findings and clinical parameters, and survival analyses using Kaplan-Meier methods and multivariable Cox regression models.

This study provides detailed insight into circulating tumor cells in high-grade serous ovarian cancer and explores their potential role as prognostic biomarkers and tools for future clinical and translational research.

Inclusion Criteria:

• Female patients aged 18 years or older.

  • Histologically confirmed high-grade serous ovarian cancer.
  • FIGO stage III or IV disease.
  • Indication for first-line platinum-based systemic therapy.
  • ECOG/WHO performance status 0-2.
  • Ability to provide peripheral blood samples.
  • Written informed consent obtained prior to participation.

Exclusion Criteria:

• Presence of another active malignancy.
• Any condition that, in the opinion of the investigators, could interfere with study participation or interpretation of results.