Breast cancer is the leading cause of death and is the most frequent disease among women. Tamoxifen is an antiestrogen used to treat breast cancer. It may completely halt the disease's progression in high-risk individuals and lower the risk of death and recurrence in premenopausal and postmenopausal women. Variations in tamoxifen responsiveness between individuals may be attributed to polymorphisms in the primary metabolizing enzyme CYP3A4. The wild genotype (GG) of rs35599367 was found to be most common in 100 female breast cancer patients who were hormone receptor positive and taking tamoxifen, according to the study. This genetic variation may have a significant impact, as the GG genotype is strongly linked to significantly lower levels of CA15.3 and estrogen. Therefore, the results of this study imply that CYP3A4 variations may be a useful predictor of a patient's prognosis and response to tamoxifen.

Keywords: CA 15.3, CYP3A4 polymorphism, Estradiol, Tamoxifen.