Difference of Relapse Pattern Between Nodal and Gastrointestinal Follicular Lymphomas

Abstract

The characteristics and treatment result of localized nodal follicular lymphoma (FL) is relatively well recognized, while those of extranodal follicular lymphomas have not been fully elucidated. The purpose of this study is to compare the relapse patterns between patients with localized nodal FL and extranodal FL, focusing on gastro-intestinal (GI) FL, treated with radiation therapy (RT) in modern era. We reviewed consecutive 70 patients with early stage FLs treated by RT with/without pharmaceutical therapy between 2005 and 2015 at single institution. All patients were histologically proven with low grade FL by expert hemato-pathologists. Information of patient characteristics, detailed RT, toxicities, relapses and salvages treatment, and outcomes were collected with chart review. The characteristics of all patients were following; median age 60 years (range, 33-79 years old), male/female: 32/38, clinical stage I: 50 II: 20, nodal 36 and extranodal 34 (Gastro-Intestinal tract 30, H&N 4). As an initial treatment, 65 patients with grade 1/2 FL were treated with radiation therapy alone and 5 patients with grade 3a FL + high tumor burden were treated with RC(H)OP+IFRT. The median radiation dose was 30.6 Gy (range, 24-40). The IFRT was delivered to the patients with nodal FL and ISRT was delivered to the patients with extranodal FL. The median follow-up time was 53 months (range 14-132). None of all patients died with FL, 2 died of other disorder, and 54 patients are alive without any evidence of relapse. The local control was achieved in 69/70 patients. One patient developed local gastric relapse. Of 36 nodal FL, 8 (22%) patients developed relapses (all of 8 relapse were systemic), while 34 extranodal FL, 6 (11%) patients developed relapse. Of extranodal FL, all relapse were patients with GI-FL, only 1 (4%) systemic relapse was recorded, and the other 5 cases were classified into local or regional relapse. The 5 loco-regional relapse sites were recognized as the organs presenting the homing receptor of GI-FL. No toxicities greater than grade 2 were observed during treatment and over follow-up time. The RT for localized follicular lymphomas provides excellent local control with low toxicities. The extranodal FL patient, especially GI-FL, has significantly lower incidence of systemic relapse than nodal FL. The RT plays more important role on the management of GI-FL than nodal FL, because of the relapse of GI-FL were few but limited within the homing sites.