Abstract
Molecular residual disease (MRD), detected by circulating tumor DNA (ctDNA) can be involved in the entire process of solid tumor management, including recurrence prediction, efficacy evaluation, and risk stratification. Currently, the detection technologies are divided into two main categories, as follows: tumor-agnostic and tumor informed. Tumor-informed assay obtains mutation information by sequencing tumor tissue samples before blood MRD monitoring, followed by formulation of a personalized MRD panel. Tumor-agnostic assays are carried out using a fixed panel without the mutation information from primary tumor tissue. The choice of testing strategy may depend on the level of evidence from ongoing randomized clinical trials, investigator preference, cost-effectiveness, patient economics, and availability of tumor tissue. The review describes the difference between tumor informed and tumor agnostic detection. In addition, the clinical application of ctDNA MRD in solid tumors was introduced, with emphasis on lung cancer, colorectal cancer, Urinary system cancer, and breast cancer.