Gene expression profiling (GEP) tests are developed to personalize treatment by selecting patients who are expected to benefit from therapy, while allowing other patients to forgo therapy.

We found that GEP testing is an effective but not a cost-effective strategy to guide the use of endocrine therapy decisions in patients with early-stage breast cancer.

GEP testing to guide endocrine therapy in early-stage breast cancer is currently not cost effective and therefore not recommended to be used in clinical practice.