Prognostic Value Of PET/CT Quantitative Metabolic Parameters In Peripheral T-cell Lymphoma

ObjectivePeripheral T-cell lymphoma(PTCL)is a highly aggressive clinical heterogeneous disease,which originates from mature T-lymphocytes after thymus,accounting for5%-20%of non-Hodgkin's lymphoma.The prognostic indicators of PTCL involve international prognostic index(IPI)and prognostic index for PTCL-U(PIT),but the prognostic value of PTCL is not uniform.Quantitative parameters of¹⁸F-FDG-PET/CT,such as maximum standard uptake value(SUVmax),total metabolic tumor volume(MTV)and total lesion glycolysis(TLG),can better reflect individual tumor load.Studies have shown that high WBTLG is a relatively independent prognostic factor in diffuse large B-cell lymphoma(DLBCL),and even better than IPI in predicting patient outcomes.Recent studies have suggested that WBSUVmax can also well indicate the prognosis of extranodal NK/T cell lymphoma(ENKTL).The aim of this study is to investigate the prognostic significance of baseline SUVmax,whole body SUVmax(WBSUVmax),WBMTV and WBTLG in patients with PTCL.MethodsEighty patients with pathologically confirmed PTCL who received PET/CT before treatment were enrolled in this study from August 2008 to May 2016.WBMTV and WBTLG were calculated by the threshold of SUV>3.0.WBSUVmax was obtained from the sum of SUVmax in extranodal lesions and in intranodal lesions.WB3SUVmax=3 lymph node regions(upper diaphragm,inferior diaphragm and spleen)and 10 additional lymph node regions(SUVmax).The optimal boundaries of WBSUVmax,WBMTV and WBTLG were obtained by using ROC analysis.According to the optimal threshold,PTCL patients were divided into high PET/CT metabolic parameters group and low PET/CT metabolic parameters group.We performed multivariate and univariate survival analysis of overall survival(OS)and progression-free survival(PFS)between the two groups.ResultsThe ROC analysis showed the optimal cut-off values with OS of WBSUVmax,WBMTV and WBTLG were 22.2(AUC=0.691;sensitivity 73.1%;specificity 69.6%;P=0.005),169.5 cm³(AUC=0.760;sensitivity 80.4%;specificity 63.6%;P<0.001)and746.1(AUC=0.772;sensitivity 85.3%;specificity 63.6%;P<0.001),respectively.According to the optimal threshold,PTCL patients were divided into high/low PET/CT SUVmax,WBMTV,WBTLG and WBSUVmax groups.The median PFS was 12 months vs.25 months(P=0.002),12 months vs.44 months(P=0.008)and 12months vs.44 months(P=0.002)in the high/low WBSUVmax,WBMTV and WBTLG groups,respectively.The median OS was 14 months vs.not reached(NR)(P<0.001),15 months vs.NR(P=0.001),and 14 months vs.NR(P<0.001).SUVmax has no predictive significance for PFS and OS.It was confirmed that WBSUVmax,WBMTV and WBTLG were correlated with IPI and PIT.In univariate analysis,the variables significantly associated with PFS and OS were WBSUVmax,WBMTV,WBTLG,stage III-IV,B symptoms,ECOG PS,positive bone marrow biopsy(BMB+),lactate dehydrogenase(LDH),IPI and PIT.The location of extranodal involvement>1 site had statistical significance only with OS.In multivariate analysis,WBTLG and PIT were independent predictors of PFS and OS.ConclusionOur study has shown that high WBTLG,WBMTV and WBSUVmax suggest a relatively poor prognosis,and a highly significant association with PIT and IPI.WBSUVmax seems easier to promote due to its operability.WBTLG appears as an independent predictor of PTCL outcome.ObjectiveExtranodal NK/T-cell lymphoma(ENKTL)is a highly aggressive lymphoma with an average survival time of less than 12 months.It has significant geographic prevalence in Asia and South America.The significance of IPI and Korean prognostic index(KPI)in ENKTL is not clear.PINK and PINKE in the pepsinase era make the prognostic evaluation of ENKTL more reasonable,but lack of prediction of treatment response.Is the prognostic value of PET/CT in ENKTL as expected as that in DLBCL? This study aims to explore the prognostic value of baseline PET/CT(B-PET)in ENKTL with SUVmax,WBMTV and WBTLG.Meanwhile,deauville five-point scale(5-DS),SUVmax,WBMTV and WBTLG of interim PET/CT(I-PET)were recorded to understand the prognostic significance of I-PET in ENKTL.MethodsSixty-three patients with ENKTL were examined by B-PET and I-PET.The SUVmax,WBMTV and WBTLG of B-PET and I-PET were recorded,and the 5-DS of I-PET was also recorded.WBMTV and WBTLG were calculated by SUV3.0.The patients were divided into high/low SUVmax,WBMTV and WBTLG groups according to the best cut-off values obtained by ROC analysis.?SUVmax,?MTV and ?TLG were obtained by subtracting the parameters of I-PET and B-PET.The optimal boundaries of ?SUVmax,?MTV and ?TLG were obtained by ROC analysis.Clinical prognostic factors were included to understand the correlation and the prognostic value between the parameters of PET/CT and clinical prognostic parameters.ResultsThe optimal cut-off values of SUVmax,WBMTV and WBTLG were 9.1(AUC 0.639;sensitivity 92.6%;specificity 36.8%;P=0.080),45.7 cm3(AUC 0.752;sensitivity80.0%;specificity 78.9%;P=0.001)and 250.4(AUC 0.738;sensitivity 80.0%;specificity 71.1%;P=0.001),respectively.The best boundary values of B-PET divided patients into two groups.We compared the difference of PFS and OS between the two groups.The median PFS of high/low SUVmax groups were 8 months vs.NR,P=0.008,the median OS of two groups were 30 months vs.NR,P=0.018.The median PFS of high/low WBMTV groups were 4 months vs.NR,P<0.001,the median OS of two groups were 6 months vs.NR,P<0.001.The median PFS of high/low WBTLG groups were 5 months vs.NR,P<0.001,and the median OS of two groups were 7months vs.NR,P<0.001.Clinical prognostic factors and B-PET quantitative parameters were included for univariate survival analysis.The prognostic factors associated with PFS were WBMTV,WBTLG,PINK,PINKE,IPI,KPI,stage and distant lymph node involvement in non-nasal lesions;the prognostic factors associated with OS were WBMTV,WBTLG,PINK,PINKE,IPI,KPI,stage,distant lymph node involvement in non-nasal lesions.Multivariate COX regression analysis showed that PINK was the only independent prognostic factor for PFS and OS,with P values of 0.008 and <0.001,respectively.Twenty-five ENKTL patients were examined by I-PET after 3-4 courses of chemotherapy.I-PET(5-DS)? 4 was positive for I-PET(I-PET+),and I-PET(5-DS)< 4 was negative for I-PET(I-PET-).SUVmax,WBMTV and WBTLG of I-PET were recorded.The median PFS in I-PET(-)and I-PET(+)groups were 6 months vs NR,P=0.010,and the median OS in both groups were 11 months vs.NR,P=0.001.I-PET(5-DS)was included in univariate and multivariate survival analysis.I-PET(5-DS)was an independent prognostic factor for OS(P=0.025),but not for PFS.ConclusionDynamic monitoring of ¹⁸F-FDG PET/CT quantitative metabolic parameters can better assess the prognosis of ENKTL.