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

Abstract

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 cm(3) was the cutoff value. The low MTV group (<220 cm(3)) had longer progression-free survival (PFS) and overall survival (OS), compared with the high MTV group (≥220 cm(3)) (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.

Fig. 1

Receiver operating characteristic curve analysis in survival prediction according to MTV in 160 stages II and III nodal DLBCL patients (continuous variable). Area under the curve was 0.857 (p < 0.001, 95% CI 0.782–0.932), and 220 cm³ was determined as the cutoff value of MTV for comparison. Sensitivity and specificity of the dichotomized MTV (≥220 versus <220) were 91.7% and 65.3%, respectively

Fig. 2

Comparisons of survival according to the cutoff value of MTV and stage combined with the cutoff value of MTV. a PFS and b OS according to the cutoff value of MTV were higher in the low MTV group compared with the high MTV group (PFS <0.001; OS, p < 0.001, respectively). c PFS and d OS of stages II and III with the low MTV groups were higher compared with other groups, whereas survival between the two low MTV groups (PFS 90.5% in stage II versus 88.0% in stage III, p = 0.703; OS 95.2% in stage II versus 88.0% in stage III, p = 0.268) or high MTV groups (PFS 60.5% in stage II versus 51.2% in stage III, p = 0.347; OS 65.8% in stage II versus 51.2% in stage III, p = 0.175) were not different