Prognostic factors and effectiveness of the first-line therapy for chronic lymphocytic leukemia: results of 10-year follow-up oleh О. B. Kalashnikova, M. O. Ivanova, N. P. Volkov, E. V. Kondakova, E. A. Izmailova, I. M. Barhatov, T. L. Gindina, E. V. Babenko, A. D. Kulagin, N. B. Mikhailova, I. S. Moiseev