RESUMEN
Radiation therapy (RT) to doses of 24-30 Gy is used for the treatment of indolent B-cell lymphoma (BCL);however, significant acute and late ocular effects are common. We aimed to develop a response adapted (RA) strategy that maintains excellent disease outcomes but reduces orbital morbidity. We performed a phase II prospective study of a RA strategy in 50 patients (pts) with stage I-IV orbital indolent BCL. Pts were treated with ultra-low dose (ULD) RT to 4 Gy in 2 fractions and assessed in 3-month intervals for response. Pts with persistent orbital lymphoma were offered an additional 20 Gy in 10 fractions. Pts that had a complete response (CR) to ULD RT were observed. We also evaluated this treatment strategy in a separate 55 pt retrospective cohort. From July 2015-January 2021 51 pts were enrolled. Fifty evaluable pts had follow-up for study inclusion. The median age was 63 years (29-88);62% were female (n=31). Pts had MALT lymphoma (n=32, 64%), follicular lymphoma (FL, n=16, 32%) and low grade BCL (n=6, 12%). Most pts (62%, n=31) had stage I disease limited to one (n=28) or both (n=3) orbits. Pts had newly diagnosed (n=36, 72%);relapsed (n=9, 18%) and refractory lymphoma (n=5, 10%). At a median follow up of 35 months [95% CI 22.2 – 37.4], 90% of pts (n=45) experienced a CR to RA RT, including 44 pts that had a CR to ULD RT (median time to CR 3.4 months) and 1 pt that had a CR after an additional 20 Gy. No local recurrences were observed. Treatment was well tolerated with no grade ≥3 toxicity. Five pts did not have a CR to planned RA therapy including 1 pt that refused additional RT, one pt treated with rituximab, one pt that had a PR on initial evaluation but has not returned for subsequent in person evaluations due to COVID, one pt being observed with stable disease and a final pt that received an additional 20 Gy to the orbit that has a persistent stable mass after the 20 Gy. In a planned subset analysis of 26 pts with newly diagnosed stage 1 disease (MALT, n=22;FL, n=3;low grade BCL, n=1);92.3% (n=24) had a CR to RA RT, with one pt requiring an additional 20 Gy. For all 26 pts with newly diagnosed stage 1 disease, the 3-year freedom from distant relapse rate was 90.4% with 3 distant relapses (contralateral orbit, n=2;paratracheal nodes, n=1). The median follow-up among the 55 pts (MALT, n=38;FL, n=13;low grade B-cell lymphoma, n=4) treated in the retrospective cohort between March 2013 and October 2021 was 28.7 months (95% CI 21.2 - 36.1);98% (n=54) of pts had a CR with RA RT, including 2 pts with a CR after an additional 20 Gy. The remaining pt went on to receive systemic therapy in lieu of additional RT for persistent disease. Among the 54 pts that had a CR with RA RT there was one local relapse in a pt with conjunctival FL 27.8 months after experiencing a CR to ULD RT. This pt received 20 Gy with resolution of the locally relapsed disease. We observed excellent disease control with negligible toxicity in the first prospective study assessing this novel approach of RA ULD RT for pts with indolent B-cell lymphoma. [ FROM AUTHOR] Copyright of International Journal of Radiation Oncology, Biology, Physics is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
RESUMEN
Purpose/Objective(s): The COVID19 pandemic required radiation oncologists (ROs) to consider shorter treatment courses to minimize patient and staff exposure and conserve healthcare resources. Hematologic ROs adopted hypofractionated radiation therapy (hRT) regimens according to guidelines published by the International Lymphoma Radiation Oncology Group (ILROG). We report for the first time the preliminary efficacy and toxicity of these novel hypofractionated regimens in the treatment of hematologic malignancies. Materials/Methods: We conducted a multicenter, multinational retrospective study under the direction of the ILROG. All patients receiving hRT according to ILROG guidelines from 1/1/2020 to 8/31/2020 were included. Patient and treatment details were abstracted from separate institutional databases. Toxicity was graded using CTCAE v5.0. Results: Ninety-three patients from 4 institutions treated with 114 RT courses were included. Patient and treatment details are displayed in Table 1. Median follow up for the cohort was 179 days, and 77 patients (82%) were alive at last follow up. Maximal toxicity experienced by patients included Grade 1 (n = 16), Grade 2 (n = 1) and Grade 3 (n = 1) toxicities. Of 80 sites with response assessment within the RT field, 69% of patients achieved a complete response (n = 55), 20% partial response (n = 16), 9% stable disease (n = 7), and 2% progressive disease (n = 2). No COVID19 infections during or after RT have been documented in this patient cohort. Conclusion: HRT according to ILROG guidelines resulted in low rates of acute toxicity and reasonable short-term treatment efficacy. Longer follow up and comparison with control groups is needed to draw more definitive conclusions and will be presented at the Annual Meeting.