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Scientific Session 11 — Nuclear Medicine

Tuesday, May 2, 2017

Abstracts 2214-3136



3136. FDG PET/CT in the Staging of Indolent Lymphoma: A Prospective Multicenter PET Registry Study

Metser U1,2*,  Tau N1,2,  Langer D3,  MacCrostie P3,  Mak V3 1. University Health Network, Mount Sinai Hospital & Women's College Hospital, Toronto, Canada; 2. University of Toronto, Toronto, Canada; 3. Cancer Care Ontario, Toronto, Canada

Address correspondence to U. Metser (umetser@gmail.com)

Objective: The purpose of this study was to measure the clinical impact of pretreatment FDG-PET/CT on the staging and management of apparent limited-stage indolent lymphoma being considered for curative radiation therapy.

Materials and Methods: This prospective, multicenter registry study included 197 patients accrued between May 1, 2012, and December 31, 2015. Pretreatment PET stage as determined by clinical data and CT was documented. If the pretreatment PET stage was indeterminate, the referring oncologist assigned a stage according to best clinical judgment. After PET, revised stage and planned management were recorded and compared with the actual treatment received, as abstracted from provincial administrative databases (n = 155).

Results: PET resulted in the upstaging of 47 patients (23.9%) with presumed limited-stage disease (stages I and II) to advanced-stage disease (stages III and IV) (p < 0.0001). Eleven patients (5.6%) were downstaged after PET, with four (2% of the cohort) migrating from advanced to limited-stage disease. In 28 of 197 patients (14.2%) with a specific pretreatment PET stage, equivocal PET findings required further evaluation to confirm disease extent. After PET, treatment was planned for 95 patients (61.3%), with 65 indicated as planned radiotherapy. However, of these 65 patients, only 38 (58.5%) received radiotherapy (p = 0.0012); nearly 75% of those (n = 28) had confirmed limited-stage disease by the PET scan.

Conclusion: For apparent limited-stage indolent lymphoma, PET may upstage nearly a quarter of patients to advanced stage disease. This results in altered management plans, with only one in four patients ultimately receiving radiotherapy. PET should be routinely incorporated into the workup of patients with presumed limited-stage indolent lymphoma being considered for curative intent radiotherapy.