Updates on Systemic Treatments for ER+ and PR+ Breast Cancers

Breast cancer is the most frequently diagnosed cancer in women. Around 5–10% of casesare metastatic at diagnosis, and close to 30% of patients with early stage disease will go on torelapse with metastatic disease. Hormone receptor-positive breast cancer makes up 70% of breastcancers cases. Endocrine therapy remains the mainstay of early treatment. significant number ofthese patients will develop either primary or secondary endocrine resistance, prompting the need fornewer treatment options. Endocrine therapy has historically formed the basis of treatment ofmetastatic hormone receptor-positive breast cancer. The development of endocrine resistance hasled to the development of newer endocrine drug combinations. Use of the CDK4/6 inhibitors hassignificantly improved progression-free survival in this group of patients. There are multiple studiesof the use of P13K inhibitors and mTOR inhibitors for use as subsequent lines of therapy,particularly for endocrine resistance. The optimal sequencing of therapy should be based on medicalcomorbidities, prior adjuvant therapies, quality of life, side-effect profile, and disease-free interval.