Evolving Significance of Tumor-Normal Sequencing in Cancer Care

Molecular tests assist at various stages of cancer patient management, including providing diagnosis, predicting prognosis, identifying therapeutic targets, and determining hereditary cancer risk. The current testing paradigm involves germline testing in a subset of patients determined to be at high risk for having a hereditary cancer syndrome, and tumor-only sequencing for treatment decisions in advanced cancer patients. A major limitation of tumor-only sequencing is its inability to distinguish germline versus somatic mutations. Tumor-normal sequencing has emerged as a comprehensive analysis for both hereditary cancer predisposition and somatic profiling. Here, we review recent studies involving tumor-normal sequencing, discuss its benefits in clinical care, challenges for its implementation, and novel insights it has provided regarding tumor biology and germline contribution to cancer.