Pancreatic cancer is a disease that carries a poor prognosis. Accurate tissue diagnosis is required. Tumours contain a high content of stromal tissue and therefore biopsies may be inconclusive. Circulating tumour cells (CTCs) have been investigated as a potential “liquid biopsy” in several malignancies and have proven to be of prognostic value in breast, prostate and colorectal cancers. They have been detected in patients with localised and metastatic pancreatic cancer with sensitivities ranging from 38%-100% using a variety of platforms. Circulating tumour DNA (ctDNA) has also been detected in pancreas cancer with a sensitivity ranging from 26%-100% in studies across different platforms and using different genetic markers. However, there is no clear consensus on which platform is the most effective for detection, nor which genetic markers are the most useful to use. Potential roles of liquid biopsies include diagnosis, screening, guiding therapies and prognosis. The presence of CTCs or ctDNA has been shown to be of prognostic value both at diagnosis and after treatment in patients with pancreatic cancer. However, more prospective studies are required before this promising technology is ready for adoption into routine clinical practice.
Potential roles of liquid biopsy
As a screening tool: As a non-invasive biopsy in patients not fit for invasive procedures or as an adjunct test where an FNA biopsy has proven inconclusive; As a biomarker used after surgical treatment to identify patients at high risk of local recurrence or distant metastasis; As a marker of prognosis in all patients prior to therapy; As a marker of chemotherapy efficacy; In the development of cell lines from circulating tumour cells; and In the detection of therapeutic targets or resistance mechanisms.