“Comparative Efficacy of Anastrozole, Letrozole, and Fulvestrant As Endocrine Partners Combined With CDK4 6 Inhibitors in Patients With HR+ HER2– Metastatic Breast Cancer: A Real-World Evidence from the Stavropol Regional Clinical Oncology Center”. Voprosy onkologii 71, no. 6 (December 30, 2025): OF-2376. Accessed October 14, 2026. https://voprosyonkologii.ru/index.php/journal/article/view/6-25-Comparative-Efficacy.