Clinical characteristics and outcomes of primary versus secondary gastrointestinal mantle cell lymphoma.

Primary gastrointestinal (GI) mantle cell lymphoma (MCL) is rare and the optimal management is unknown. We reviewed 800 newly diagnosed MCL cases and found 22 primary (2.8%) and 79 (9.9%) secondary GI MCL cases. Age, sex, and performance status were similar between primary and secondary cases. Secondary cases had more elevations in lactate dehydrogenase (28% vs 0%, P = 0.03) and a trend for a higher MCL international prognostic index (P = 0.07). Observation or local therapy was more common for primary GI MCL (29% vs 8%, P < 0.01), and autologous stem-cell transplant was more common for secondary GI MCL (35% vs 14%, P < 0.05). The median follow-up was 85 months. Primary and secondary GI MCL had similar 5-year progression-free survival (PFS) (30% vs 28%, P = 0.59) and overall survival (OS) (65% vs 66%, P = 0.83). The extent of GI involvement in primary GI MCL affected treatment selection but not outcome, with a 5-year PFS of 43% vs 14% vs 31% (P = 0.48) and OS of 57% vs 71% vs 69% (P = 0.54) in cases with single lesion vs multiple lesions in 1 organ vs multiple lesions in ≥2 organs. Less aggressive frontline treatment for primary GI MCL is reasonable. It is unknown whether more aggressive treatment can result in improved outcomes.