Clinical significance of metabolic tumor volume by PET/CT in stages II and III of diffuse large B cell lymphoma without extranodal site involvement

The objective of this study was to investigate whether metabolic tumor volume (MTV) by positron emission tomography (PET) can be a potential prognostic tool when compared with Ann Arbor stage, in stages II and III nodal diffuse large B cell lymphoma (DLBCL). We evaluated 169 patients with nodal stages II and III DLBCL who underwent measurements with PET prior to rituximab combined with cyclophosphamide, adriamycin, vincristine, and prednisone (R-CHOP). Cutoff point of MTV was measured using the receiver operating characteristic (ROC) curve. During a median period of 36 months, stage II was 59.2% and III was 40.8%. Using the ROC curve, the MTV of 220 cm³ was the cutoff value. The low MTV group (<220 cm³) had longer progression-free survival (PFS) and overall survival (OS), compared with the high MTV group (≥220 cm³) (p < 0.001, p < 0.001). Stage II patients had longer survival than those in stage III (PFS, p = 0.011; OS, p = 0.001). The high MTV group had lower PFS and OS patterns, regardless of stage, compared with the low MTV group (p < 0.001, p < 0.001). Multivariate analysis revealed an association of the high MTV group with lower PFS and OS (PFS, hazard ratio (HR) = 5.300, p < 0.001; OS, HR = 7.009, p < 0.001), but not stage III (PFS, p = 0.187; OS, p = 0.054). Assessment of MTV by PET had more potential predictive power than Ann Arbor stage in the patients that received R-CHOP.