Hematologic Cancer

PV QA 2 - Poster Viewing Q&A 2

MO_43_2821 - Outcome and Role of Radiation Therapy in Stage I-II Mesenteric Diffuse Large B-Cell Lymphoma

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Outcome and Role of Radiation Therapy in Stage I-II Mesenteric Diffuse Large B-Cell Lymphoma
M. X. Qu1,2, M. Jones1,2, R. W. Tsang1, D. Hodgson2, A. Sun1, M. Crump3,4, and M. Gospodarowicz1; 1Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada, 2Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada, 3Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, Toronto, ON, Canada, 4Department of Medicine, University of Toronto, Toronto, ON, Canada

Purpose/Objective(s): Limited stage DLBCL in the mesentery is an uncommon presentation. There is debate on the role and technique of RT in this disease both in terms of the need for RT, and targeting a mobile mesentery. We examined the outcome and role of combined modality therapy (CMT) policy in stage I-II DLBCL.

Materials/Methods: All patients (pts) presenting with stage I-II mesenteric DLBCL at our center between 2000 to 2016 were reviewed (n=48). The median age was 63 years (range 24-81) and 65% (n=31) were men. All patients were staged with CT and bone marrow biopsy and 8% (n=4) were staged with PET-CT. Stage II presentation was in 88% (n=42) with paraaotic (69%, n=33) and/or iliac (19%, n=9) nodal regional sites involved. International prognostic index (IPI) of 0-1 was documented in 38% (n=18). Bulky disease (≥7.5cm) was seen in 71% (n=34). Most pts (n=40, 83%) received RCHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), 10% (n=5) had CHOP and 6% (n=3) had mixed regimens. A total of 33 pts received consolidative RT and completed as planned. The median dose was 35Gy in 20 fractions (range 30-36 Gy). Most pts had involved site RT (ISRT; planned target volume: median 1235 cc, range 317-4557cc) except 2 had whole abdominal RT. IMRT was used in 55% (n=18) following ISRT principles with CTV to PTV margin of 1-2cm. Treatment response was assessed based on the Lugano response criteria with PET-CT (42%,n=20) and International Working Group response criteria with CT.

Results: The median follow-up was 3.7 year (range 0.4-13). After initial chemotherapy, 35 pts (73%) had complete response (CR/CRu), 8 (17%) had partial response (PR), 1 had stable disease (SD) and 4 had progressive disease (PD). Among those in CR/CRu, 25 (71%) received consolidation RT, and 10 did not due to referring physician/patient choice. All 8 pts with PR underwent RT and remained disease free. Four out of five pts (80%) who had SD/PD after initial chemotherapy died of the disease within a short time (5 - 13 months). Among the 43 pts with CR/CRu/PR to initial chemotherapy, 2 (5%) relapsed of which one had CMT (1 of 25 CR/CRu patients, 0 of 8 PR patients) and one had RCHOP only (1 of 10 CR/CRu patients). The 5-year overall survival, progression free survival and local control rates were 81% (95%CI 68-95%), 81% (95%CI 68-93%) and 83% (95%CI 71-95%) respectively. Among the 33 pts who had consolidative RT, 1 had G3 acute toxicity (GI bleeding, small bowel involvement at presentation) and there was no G2 or above late toxicity.

Conclusion: Stage I-II mesenteric DLBCL has a favorable outcome similar to other sites when treated with combined modality therapy or chemotherapy alone. ISRT for mesenteric lymphoma is feasible and well tolerated. We are unable to assess whether consolidative RT is required following a CR to chemotherapy due to small sample size, and low number of events.

Author Disclosure: M. Qu: None. M. Jones: None. R.W. Tsang: None. D. Hodgson: Co-chair, Proton Advisory Committee; Cancer Care Ontario. Vice-chair, Hodgkin Lymphoma Committee; Children's Oncology Group. A. Sun: None. M. Gospodarowicz: None.

Melody Xuanlu Qu, MD

Princess Margaret Cancer Centre


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MO_43_2821 - Outcome and Role of Radiation Therapy in Stage I-II Mesenteric Diffuse Large B-Cell Lymphoma

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