Participants that have been hospitalized for MCL after January 1st 2009.

Biopsy proven MCL as evidenced by histology with either immunohistochemistry (IHC) or t(11,14) translocation

Retrospective group: Participants who have finished BTZ treatment before the study initiation as judged by participating site physician

If participant isn't accessible for oral or written informed consent, ICF can be waived after approved by the IRB

Prospective group: Participants who are on BTZ at the time of study initiation or start BTZ after study initiation

Study of Bortezomib (BTZ) Treatment on Mantle Cell Lymphoma (MCL) in Chinese Participants