Observational Study for Patients With Newly Diagnosed (MCL) Not Eligible for High-dose Therapy

This is an observational study considered for patients with mantle cell lymphoma meeting the basic inclusion criteria. The study will enrol patients who will be treated according to standard protocol used in the hematologic department. Scheme of treatment: alternating cycles of R-CHOP and R-AraC: R-CHOP / R-AraC / R-CHOP / R-AraC / R-CHOP / R-AraC. Baseline procedures: * CT or PET-CT (positron emission tomography with computed tomography)before starting treatment, after 3 cycles and at the end of treatment (after 6 cycles) * bone marrow examination before therapy, after 3 cycles and after completion of induction * maintenance rituximab based of standards of each centre The study was proposed based on the previously published data in the younger patients, which demonstrated improved outcome after implementation of Ara-C into induction. Primary objectives include response after induction by PET-CT and PFS (progression-free survival). Secondary objectives include OS (overall survival), and prognostic significance of minimal residual disease detection after completion of induction