Successful Management of Diffuse Large B-Cell Lymphoma Involving the Mesentery with Volumetric Image Guided Intensity Modulated Radiation Therapy

Abstract

Due to the potential for unpredictable motion of mesenteric masses, there may be reluctance to administer radiation therapy (RT) for diffuse large B- cell lymphoma (DLBCL) with mesenteric nodal involvement. We report the outcome of patients treated with RT to mesenteric adenopathy with involved site radiation therapy (ISRT), intensity modulated radiation therapy (IMRT) and daily CT image guidance. Patients treated for DLBCL with RT to the mesentery between 2011-2017 were reviewed. Eligible patients had RT for consolidation or definitive treatment targeting all sites of evident disease. Clinical and treatment characteristics were analyzed for an association with local control (LC), progression free survival (PFS) and overall survival (OS). Twenty-four patients were eligible for analysis. At diagnosis, the median age was 52 years (39-77), and 54% (n=13) had stage I/II DLBCL. All patients received frontline chemotherapy (ChT) (R-CHOP, n=20; dose adjusted R-EPOCH, n=4) with a median of 6 cycles. Salvage ChT for refractory DLBCL was given prior to RT in 46% (n=11) and autologous stem cell transplantation was administered in 13% (n=3) before RT. At the time of RT, PET-CT imaging revealed 5PS of 1-3 in 46% (n=11), 5PS of 4 in 12% (n=3) and 5PS of 5 in 42% (n=10). All patients received IMRT, daily CT imaging and ISRT. The median RT dose was 40 Gy. After RT, relapse or progression occurred in 22% (n=5). Two patients progressed, 2 relapsed, and one had a residual avid mass in-field that has been followed for 12 months without additional therapy. Disease relapse/progression occurred locally (within field) for 2 patients, distant (outside of the abdomen) in 1 patient, and combined distant and local in 2 patients. The median time to local failure, PFS, and OS were not reached. At a median follow up of 37 months, the 3-year LC, PFS and OS rates were 81%, 76% and 96% respectively. Among patients treated with consolidative RT after successful frontline ChT (n=9), 3-year PFS was 100%, compared to 64% for patients with a history of chemorefractory DLBCL (n=16, p=0.07). Comparing patients with 5PS 1-3 after ChT to those with 5PS 4-5, there was no difference in time to local recurrence, PFS, or OS (p= 0.27, 0.31, 0.10). 4 of the 5 relapses occurred in patients with 5PS of 5 prior to RT. Patients with 5PS of 5 (n=10) had a median of 3 lines of ChT prior to RT and 3-year PFS of 56%, compared to 1 prior line of ChT and 3-year PFS of 92% for those with 5PS of 1-4 (n=14, p=0.098). Two deaths occurred due to DLBCL (n=1) or myelodysplastic syndrome (n=1). Patients with DLBCL involving the mesentery can be successfully treated with image-guided IMRT and ISRT. Outcomes for patients treated with combined modality therapy for chemosensitive disease are excellent. Even among patients with highly refractory and heavily pretreated DLBCL with a 5PS of 5, RT offers disease control in roughly half of patients.