Impact of salvage treatment modalities in patients with positive FDG-PET/CT after R-CHOP chemotherapy for aggressive B-cell non-Hodgkin lymphoma.

Introduction: To compare outcomes of different salvage treatment modalities in patients with aggressive B-cell non-Hodgkin lymphoma (NHL) who remain FDG-PET positive after R-CHOP chemotherapy. Existing data on these patients with FDG-PET primary refractory disease are limited.

Methods: Patients with diffuse large B-cell lymphoma or grade 3 follicular lymphoma were retrospectively reviewed from the Prince of Wales Hospital databases. Eligibility criteria were: age≥18 years, treated with R-CHOP, with positive post-chemotherapy FDG-PET. Salvage treatment modalities were: radical radiotherapy (RT, dose≥30 Gy), high dose chemotherapy and autologous stem cell transplant (ASCT), or non-radical management. Survival was calculated from date of post-chemotherapy FDG-PET to last follow-up.

Results: Twenty-six patients from 2003-2015 met the inclusion criteria. Median age was 60 (range 19-84). Most had adverse baseline features: 21 (81%) stage III-IV, 24 (92%) bulky disease and nine (35%) skeletal involvement. Characteristics of PET-positivity post-chemotherapy were single site in 16 (62%), sites of prior bulk in 24 of 24, skeletal sites in five of nine, and able to be encompassed by RT in 21 (81%). Salvage treatment was: radical RT in 17 (65%), ASCT in four (15%) and non-radical in five (20%). Median follow-up of surviving patients was 31 months. Kaplan-Meier estimates of 3-year PFS and OS were 41% and 52%, respectively. By salvage modality, 3-year PFS was 51% for RT, 25% for ASCT and 20% for non-radical treatment, (P = 0.453); 3-year OS was respectively 65%, 25% and 40% (P = 0.173).

Conclusion: Patients with FDG-PET positive disease after R-CHOP for aggressive B-cell NHL are salvageable with radiotherapy.