Molecular Testing and Liquid Biopsy for Ovarian Cancer

Jianyu Rao, MD Professor and Vice Chair, UCLA Medical Center, Los Angeles, CA, USA.

Molecular testing, such as testing of Tumor Homologous Recombination Deficiency (HRD), is important for managing ovarian cancer patients, as it provides the guidance of PARP inhibitor–based targeted therapy. However, molecular testing using tissue sample suffer many shortcomings. Obtaining tissue sample requires invasive procedures, as the patient may be too ill to undergo open biopsy. Other major problems include the heterogeneous nature of tissue sample with a mixture of stroma and tumor that may contain a variety of histological patterns, and difficulty in obtaining high-quality and quantity tumor DNA extracted from FFPE sections. It has been estimated that, for NGS based analysis, anywhere between 5 to 40% tissue samples do not yield sufficient high quality/quantity DNA for the testing (Kris, et al, JAMA 2014, and Morris, et al, Plos One 2018). On the other hand, liquid specimens including body fluid such as ascites and pleural fluid and blood provide alternative sample source for molecular testing. In this discussion, we will discuss some basic concepts of liquid biopsy and ovarian cancer in general, the perspectives and challenges of using it in managing as well as detection of ovarian cancers.