ASO Author Reflections: Potential Values of Peritoneal Cell-Free Tumor DNA Testing

Excerpt

Circulating cell-free tumor DNA (ctDNA) has been emerging as a useful biomarker for clinical oncology in recent years.1 Monitoring of treatment response and disease progression, and early detection of recurrence after curative treatment are some examples of the utility of ctDNA testing for various cancers.1 While ctDNA testing using circulating blood samples is widely accepted among oncologists, the predictive value of ctDNA testing using circulating blood samples for patients with isolated peritoneal metastases has been debated. Using the next-generation sequencing (NGS) method, Baumgartner et al.2 showed that only 39% (31/80) of patients with peritoneal carcinomatosis had positive ctDNA in their blood samples. Using droplet digital PCR (ddPCR) detecting KRAS mutations, Sugimori et al. showed that 96% (45/47) of patients with pancreatic ductal adenocarcinoma (PDAC) had KRAS mutations in their primary tumors, but only 51% (23/45) of the KRAS mutated locally advanced or metastatic PDAC patients had positive ctDNA in their blood. Interestingly, while KRAS mutant ctDNA was detected in 95% (18/19) of KRAS mutated PDAC patients with hepatic or pulmonary metastases, only 33% (3/9) of PDAC patients with peritoneal metastasis had positive KRAS mutant ctDNA in their blood samples.3 These studies raise a genuine concern on the usefulness of circulating ctDNA testing in patients with isolated peritoneal metastasis. …