This is a multicentric, observational and retrospective study of the use of lenalidomide in patients with relapsed or refractory mantle cell lymphoma that are included in the RRMCL spanish program.

The lenalidomide effectiveness and tolerability data will be retrospectely collected until the 30 of April 2018.

Inclusion Criteria:

• ≥ 18 years old.
• Diagnosed with relapsed or refractory mantle cell lymphoma verified by a tissue biopsy.
• Treated with monotherapy or combination of lenalidomide.
• Not candidate for any of the therapeutic options approved until that date for this disease.
• Not candidate or unable to be included in any clinical trial due to availability or geographical difficulty.
• Registered in the RRMCL spanish program.

Exclusion Criteria:

• ECOG > 2.
• Patients with uncontrolled comorbidities.
• Blastoid variant.
• Central nervous system tumor infiltration.
• HIV, HBV and/or HCV active infection.
• Radiotherapy concomitant treatment or that have received radiotherapy in the previous 30 days to the beginning of the first cycle of lenalidomide.
• Diagnosed with other active solid tumor except for basal cell carcinoma skin cancer.
• Patients that haven´t completed at least one complete cycle of the treatment.

Adult patients diagnosed with mantle cell lymphoma that received lenalidomide through the RRMCL program as long as they meet all the inclusion criteria and none of the exclusion and independently from being dead or alive in the moment of data record.