Association of FDG PET-CT (PET) avid skeletal lesions (SL) with progression-free survival (PFS) in patients (pts) with previously untreated follicular lymphoma (FL).

Abstract

e19026 Background: PET scan is frequently utilized in FL. Reduced EFS has been observed in DLBCL pts with SL treated with RCHOP (Held, JCO 31:4115, 2013). Methods: We performed a retrospective single center study to assess outcomes of FL pts with PET avid SL between January 2005 and November 2015. 131 pts with newly diagnosed FL and PET performed within 1 month of diagnosis were included. Results: 32 of these pts had SL (median 4, range 1-11) on initial PET. Median age was 57 (range 43-79), 15 (47%) were female, 30 (94%) had stage IV disease, LDH was elevated in 6 (19%), 6 (19%) had bulky disease > 6 cm, and FLIPI-1 score was low in 5, intermediate in 11, and high 16 pts. 27 pts had grade (gr) 1-2 FL, 2 had gr 3a, and 3 had gr 3 (not classified). All but 1 patient received rituximab (R)-containing therapy (9 received BR, 7 received RCHOP, 5 RCVP, 9 other). 8 pts received maintenance R, and none received radiation. There were no statistically significant differences in median age, tumor gr, LDH, or use of anthracycline containing therapy (28% in SL group vs 16% in non-SL group, p = 0.13) in pts with SL compared to those without SL (n = 99). Pts with SL had higher incidence of bone marrow involvement (27% vs 9%, p = 0.013). With a median follow-up of 35 months, SL pts had 44% rate of transformation to DLBCL compared 12% in non-SL pts (p = 0.004). Median PFS was 45.8 months in SL pts not-reached in non-SL pts (p = 0.003). Median OS was 105.9 months in SL pts and not reached in non-SL pts (p = 0.08). In the multi-variate analysis, SL (p = 0.037), male gender (p = 0.048), higher FLIPI-1 score (p = 0.009), and absence of anthracycline containing therapy (p = 0.005) were significantly associated with decreased PFS using backward selection. Conclusions: The presence of PET identified SL in previously untreated FL is associated with an increased risk of transformation and reduced PFS in this single center retrospective analysis. Larger studies of uniformly treated pts are needed to validate these data. The identification of high-risk PET avid SL in FL pts in future prospective therapeutic trials could be used to select pts for specific induction regimens, maintenance rituximab, or consolidative radiation.