The use of FDG-PET to guide consolidative radiotherapy in patients with advanced-stage Hodgkin lymphoma with residual abnormalities on CT scan following ABVD chemotherapy.

Abstract

8034 Background: Consolidative radiotherapy (RT) is frequently administered following chemotherapy (CHT) for advanced stage Hodgkin lymphoma (HL) patients who have bulky disease at diagnosis and/or residual abnormalities on post-CHT CT imaging. The GHSG HD15 trial has recently shown that RT can be omitted in cases that have residual disease on CT imaging following BEACOPP-based CHT but are FDG-PET-negative (PET-neg). However, it is unknown whether this also applies to patients treated with ABVD CHT and to those with initial bulky disease. Further, the effectiveness of RT for cases that are PET positive (PET-pos) following ABVD CHT remains unclear. Methods: Since July 2005, adult (> 16 y) patients in British Columbia (BC) with advanced stage HL (stage III /IV and/or the presence B symptoms and/or bulky disease [> 10cm]) have been recommended to undergo FDG-PET imaging if residual abnormalities > 2 cm are seen on the post CHT CT scan. If the PET scan was negative, patients were observed, regardless of initial disease bulk. If the PET scan was positive RT was administered, if feasible. Results: In total, 163 patients responding patients have had a PET scan following curative intent ABVD or equivalent CHT: PET-neg 80% (n=130); PET-pos 19% (n=31); PET-indeterminate 1% (n=2). Patient characteristics include: M:F 1:1.04; median age, 31 y (17-76 y); stage II, 52%; bulky disease, 50%; B symptoms, 68%; IPFP Prognostic score > 3, 15%. With a median follow-up of 34 months, patients with a PET-neg scan post CHT have a far superior 3-year TTP compared to those with a PET-pos scan (89% vs 55%, p= .00001). In the PET-neg patients, there was no difference in the 3-year TTP in those with bulky vs non-bulky disease at diagnosis (86% vs 91%, p=.71). In the PET-pos group, 25 (81%) received the planned RT and of these, 10 (40%) have relapsed. Conclusions: Advanced stage HL patients with a negative PET scan following ABVD CHT are at low risk of relapse and do not routinely require additional consolidative RT thus avoiding potential long-term side effects. Although some patients with a positive PET-scan remain disease free after consolidative RT, a high proportion ultimately relapse.