Cancer Cytopathology: NGS on ascites rivals tissue

Next-generation sequencing is a gene-reading test doctors use to find DNA changes that can steer cancer treatment. A new Cancer Cytopathology study says the test also works on malignant ascites, the fluid that builds up in the abdomen in many ovarian cancers. (pubmed.ncbi.nlm.nih.gov) The paper focused on high-grade serous ovarian carcinoma, the most common and deadliest ovarian cancer subtype. In this disease, fluid in the peritoneal cavity often contains tumor cells and is commonly drained as part of care. (pubmed.ncbi.nlm.nih.gov) (acsjournals.onlinelibrary.wiley.com) Standard practice usually tests formalin-fixed, paraffin-embedded tissue taken at surgery or biopsy. That can be a bottleneck when tissue is scarce, delayed, or too poor in quality for sequencing. (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov) Chiara Pighi and colleagues analyzed 34 ascites-derived cytology samples with an amplicon-based next-generation sequencing assay for BRCA1/2. They compared those results with matched surgical specimens that had already been tested in routine practice. (pubmed.ncbi.nlm.nih.gov) (acsjournals.onlinelibrary.wiley.com) The match was exact for every pathogenic BRCA1/2 variant the team found. The study reported 100% concordance between ascites samples and tissue, covering both inherited, or germline, variants and tumor-only, or somatic, variants. (pubmed.ncbi.nlm.nih.gov) The authors also said sequencing remained feasible in archived ascites material and in samples with low tumor fraction. That matters because fluid specimens are often mixed with non-cancer cells, which can dilute the signal labs are trying to read. (pubmed.ncbi.nlm.nih.gov) BRCA1/2 results can affect treatment because tumors with these defects may respond to poly(adenosine diphosphate-ribose) polymerase, or PARP, inhibitors. Guidelines and laboratory recommendations already treat tumor BRCA testing as a routine part of ovarian cancer workups. (pubmed.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov) (interactiveguidelines.esmo.org) The study was small and limited to 34 cases from a specific clinical setting, and it tested BRCA1/2 rather than a broad multigene panel. The authors framed it as evidence that ascites can serve as a minimally invasive substitute when tissue is unavailable. (pubmed.ncbi.nlm.nih.gov) That leaves a practical takeaway for pathology labs and oncology teams: the fluid already drained to diagnose or relieve symptoms may also carry the genetic answer needed to start targeted treatment planning. (acsjournals.onlinelibrary.wiley.com 1) (acsjournals.onlinelibrary.wiley.com 2)