JSH practical guidelines for hematological malignancies, 2018: II. Lymphoma-1. Follicular lymphoma (FL)

Excerpt

Follicular lymphoma (FL) is a major type of indolent (low-grade) B-cell lymphoma that accounts for 10–20% of all non-Hodgkin lymphomas [1]. The prevalence of FL has recently been increasing in Japan [2]. FL is histopathologically classified into grades 1, 2, 3A, and 3B, but grade 3B is typically treated as aggressive (intermediate- to high-grade) lymphoma. It is diagnosed from lymph node enlargement in almost all patients, and about 70–85% of patients have advanced (clinical stage III/IV) disease on diagnosis, and bone marrow involvement is frequently observed as well. Although there has recently been much attention on extranodal FL localized to the gastrointestinal tract or skin, this guidelines will primarily cover nodal FL. FL typically has an indolent course and initially responds well to chemotherapy. However, it is typical for FL patients to experience repeated relapses, and this trend is particularly strong with advanced disease. An analysis conducted after the introduction of rituximab showed that histologic transformation to aggressive lymphoma occurred in about 10% of patients over a 5-year period. Although median survival time for FL patients was previously considered to be 7–10 years based on data from before the introduction of rituximab, recent studies have shown median survival time of over 20 years for patients diagnosed at age 40 or younger [3]. …