Opportunities of the pharmacogenetic approach to personalized tamoxifen breast cancer therapy: case reports oleh Marina I Savelyeva, Irina A Dudina, Juliya S Zaharenkova, Anna K Ignatova, Kristina A Ryzhikova, Zhannet A Sozaeva, Dmitriy A Kudlay, Oksana M Perfileva, Irina V Poddubnaya