Circulating tumor DNA (ctDNA) to evaluate minimal residual disease (MRD), treatment response, and posttreatment prognosis in pancreatic adenocarcinoma: ctDNA and MRD in pancreatic adenocarcinoma

Background: Circulating tumor DNA (ctDNA) has emerged as a blood-based test with multiple utilities in oncology. In the past few years, multiple studies of varying designs, methods, and quality have emerged which show promise for ctDNA as a tool to assess response to treatment and detect minimal residual disease (MRD) across various gastrointestinal (GI) malignancies. We aim to review the current literature for ctDNA as it pertains to assessing treatment response, MRD, prognosis, and risk of recurrence for pancreatic adenocarcinoma. Methods: PubMed was queried with a combination of terms regarding pancreatic adenocarcinoma, minimal residual disease, resection, and prognosis. All resultant articles were reviewed by the authors for appropriate fit with scope. Results: Fourteen articles were identified that fit with the scope of this review. Conclusions: Detectable ctDNA after definitive resection, specifically mutated KRAS, correlates with shorter recurrence-free survival (RFS), overall survival (OS), and overall prognosis. Limited data also suggests ctDNA may provide a noninvasive means to assess response to chemotherapy. Whether this information is actionable in terms of altering neoadjuvant or postresection treatment regimens remains an open question requiring further study.