Ascites Cell Blocks Enable Ovarian Cancer Diagnosis and Molecular Profiling

Ascitic fluid collected from 58 patients with ovarian cancer provided material for both immunohistochemical diagnosis and mutation testing when converted into paraffin-embedded cell blocks, according to the study. Researchers detected homologous recombination repair gene mutations in 45 patients, or 77.6% of the cohort, and identified nine BRCA1 or BRCA2 variants. The results show that these cell blocks can combine cellular characterization with molecular analysis of genes relevant to ovarian cancer.

Most patients with ovarian cancer are diagnosed at an advanced stage, when adequate solid tumor tissue for molecular testing is frequently unavailable. Malignant ascites is a common complication at this stage and represents an abundant, easily accessible source of tumor cells. The investigators prepared cell blocks from ascitic fluid obtained between January 2016 and June 2021 from 58 patients with ovarian cancer. They assessed diagnostic immunohistochemical markers, including Pax-8, WT-1, CA-125, CK7 and CK20, and used next-generation sequencing to examine 32 genes: 13 genetic or therapy-related genes and 19 homologous recombination repair genes.

Across histological subtypes, Pax-8 was expressed in 87.5% to 100% of cases, WT-1 in 87.8% to 90%, and CA-125 and CK7 in 100%. CK20 was largely negative, a different pattern from the other diagnostic markers. These observations supported the diagnostic value of the ascites-derived cell blocks. The study was a cohort analysis in 58 patients, however, and the supplied report does not describe a comparison with a separate diagnostic reference standard or establish performance in unselected clinical populations. Its scope was therefore the feasibility and characterization of the combined diagnostic and molecular approach in the enrolled group.

Mutation results showed TP53 as the most frequently altered gene, found in 50.8% of patients, followed by PIK3CA in 20.0%. The nine BRCA1/2 mutations comprised seven germline and two somatic variants, with germline and somatic status determined by comparison with matched blood samples. E545K and E542K were the most common PIK3CA variants, each accounting for 28.6% of observed PIK3CA variants. The authors proposed that homologous recombination repair status from these cell blocks could guide assessment of eligibility for PARP inhibitor therapy, while recurrent PIK3CA mutations highlight the PI3K/AKT pathway as a potential therapeutic target. The study itself did not test treatment response, progression-free survival or survival, and it did not prospectively evaluate whether cell-block-guided treatment selection improves clinical outcomes. Its central supported finding is that malignant ascites can supply a single specimen for morphological, immunophenotypic and molecular characterization of ovarian cancer, while the clinical value of using the genetic results for individualized treatment remains to be demonstrated.

Subject of Research: Diagnostic and molecular characterization of ovarian cancer using ascites-derived cell blocks

Article Title: The clinicopathological and molecular characterization in ascites-derived paraffin-embedded cell blocks of ovarian cancer

Article References: Zhang, C., Jia, W., Dong, S., Zhang, P., & Gao, J. (2026). The clinicopathological and molecular characterization in ascites-derived paraffin-embedded cell blocks of ovarian cancer. BMC Cancer. https://doi.org/10.1186/s12885-026-16703-x

Image Credits: AI Generated

DOI: 10.1186/s12885-026-16703-x

Keywords: ovarian cancer, malignant ascites, cell blocks, immunohistochemistry, next-generation sequencing, BRCA1, BRCA2, homologous recombination repair, TP53, PIK3CA, clinicopathological, molecular