Clinical implications of PET-negative residual disease at the completion of chemotherapy for diffuse large B-cell Lymphoma.

Abstract

e18516 Background: To evaluate potential differences in overall survival (OS) and progression-free survival (PFS) according to PET and CT disease status at completion of chemotherapy for patients with diffuse large B-cell lymphoma. Methods: Subjects were 303 patients with histologically confirmed DLBCL treated between January 2001 and December 2007; no patient received radiation therapy. We evaluated: age, sex, Ann Arbor stage, bulky disease, International Prognostic Index score, Ki-67 expression, PET standardized uptake values (SUVs), disease status after chemotherapy and at last follow-up. Results: Median age was 61 years; 149 men; 81 (27%) had stage I-II, 242 (73%) stage III-IV. A total of 248 patients (82%) completed 6-8 cycles of doxorubicin-based therapy. On multivariate analysis, both OS and PFS were significantly influenced by: the presence of PET negative residual mass on CT at completion of therapy (P < 0.001 for OS and P < 0.001 for PFS); number of cycles and type of chemotherapy (P < 0.001 for OS and P< 0.001 for PFS); Combined presence (p=0.01 for OS and P=0.003 for PFS) of high Ki 67, high PET SUV, and bulky disease; and IPI score (P = 0.001 for OS and P < 0.001 for PFS). Same factors remained significant when replacing response to therapy with size (> 2cm) or number of residual sites (p<0.0001 OS and p<0.0001 PFS). Conclusions: Presence of a residual mass on CT at the completion of chemotherapy has both prognostic and predictive value in patients with DLBCL. These patients should be considered for biopsy and further consolidative therapy