Neutrophil Extracellular Traps Formation in Breast Cancer Patients Taking Tamoxifen

This study looks at how tamoxifen — a common breast cancer hormone therapy — affects the immune system, specifically a type of immune activity called neutrophil extracellular traps (NETs). Researchers want to understand whether these immune changes might explain some of tamoxifen's effects in breast cancer patients. **You may be eligible if...** - You are a woman diagnosed with estrogen receptor-positive (ER+) breast cancer - You are pre-menopausal (age 18–45, or 46–50 if you still have periods) or menopausal (age 51+) - You have been taking tamoxifen for at least 6 months (or are newly starting it, for the control group) **You may NOT be eligible if...** - You are pregnant - You have a history of rare inherited conditions affecting white blood cells (e.g., Kostmann syndrome, Wiskott-Aldrich syndrome) - You have an autoimmune disease like lupus, rheumatoid arthritis, or Crohn's disease - You have a chronic viral infection such as HIV or hepatitis - You recently tested positive for COVID-19 Talk to your doctor to see if this trial is right for you.