Follicular lymphoma (FL), which belongs to the subtype of non-Hodgkin lymphomas (NHL), accounts for approximately 20% of all lymphomas in the USA [1]. In Japan, FL is the second most common subtype of NHL, accounting for 13.5% of all NHL types, followed by diffuse large B-cell lymphoma [2,3]. In addition, FL is associated with approximately 30% lifetime risk of transforming to a more aggressive lymphoma, most commonly to diffuse large B-cell lymphoma [4,5].