Among breast cancer patients, 85% belong to luminal epithelial-like breast cancer, and these patients generally need to receive hormone therapy in clinic. Tamoxifen is one of the most common hormone drugs. . Estrogen enters breast cancer cells and can bind to estrogen receptors, thereby stimulating tumor cell growth. The structure of tamoxifen is similar to that of estrogen. It can compete with estrogen for binding to estrogen receptors, preventing the exertion of estrogen, thereby inhibiting the proliferation of breast cancer cells. In clinical application, some patients were found to be "tamoxifen sensitive" and "tamoxifen resistant".

Pharmacogenomics studies have shown that polymorphisms of the CYP2D6 gene can affect the serological concentration of the active metabolite of tamoxifen. This kit detects the polymorphism of CYP2D6 gene, which is helpful to guide individualized endocrine therapy of tamoxifen, and to avoid ineffective drugs for CYP2D6 mutant individuals with no function or severe functional impairment as soon as possible.