Vyberg and colleagues analyzed the socioeconomic consequences of inaccurate HER2 test results between regulatory-approved tests and LDTs for the treatment of breast cancer, and suggested that using regulatory-approved HER2 tests rather than LDTs could result in annual savings of $46 million, largely due to correct treatment with trastuzumab and avoiding treatment costs associated with disease recurrence and progression. The gene discussed is ERBB2; the disease is breast carcinoma.