Predictive approaches for post-therapy PET/CT in patients with extranodal natural killer/T-cell lymphoma: a retrospective study

Extranodal NK/T-cell lymphoma with localized relapse in bone marrow of lower leg detected using PET-CT

Extranodal natural killer (NK)/T-cell lymphoma (ENKTL) is a rare subtype of non-Hodgkin lymphoma (NHL) with poor prognosis, particularly in relapsed or refractory patients. Thus, timely detection of relapse and appropriate disease management are crucial. We present two patients with ENKTL, wherein positron emission tomography-computed tomography (PET-CT) with total-body coverage after induction therapy, detected newly relapsed regions in the bone marrow of the lower leg prior to progression. Case 1: A 47-year-old woman with nasal obstruction, showing 18F-fluoro-deoxyglucose (FDG) uptake in the nasal cavity (Lugano stage IE). After induction therapy (RT-2/3 DeVIC), PET-CT revealed abnormal uptake only in the right fibula. Case 2: A 68-year-old man with a skin nodule/ulcer and an enlarged right inguinal lymph node was diagnosed with advanced ENKTL. A PET-CT scan revealed abnormal uptake in the subcutaneous mass of the right medial thigh, lymph nodes, and descending colon (Lugano stage IV). After induction therapy, PET-CT revealed new abnormal uptake only in the left tibia. In both patients, CT-guided biopsy confirmed ENKTL recurrence. Moreover, PET-CT with whole-body coverage was useful for the timely assessment of relapse and detection of asymptomatic bone involvement. This approach allowed for modifications to treatment strategies in certain patients.

The exact Deauville score, NABS score and high SUVmax predicts outcome in extranodal natural killer/T-cell lymphoma

OBJECTIVE

Natural killer T-cell lymphoma (NKTCL) is an aggressive type of non-Hodgkin's lymphoma. While FDG-PET/CT imaging has been increasingly utilized for disease assessment, its prognostic value and potential utility in NKTCL patient stratification remain controversial. We aim to investigate the prognostic utility of FDG-PET/CT and its role in complementing clinical indices.

METHODS

We conducted a retrospective review of 72 patients from a tertiary National Cancer Centre with biopsy-proven NKTCL and available FDG-PET/CT data (either baseline, end of treatment or both). Survival analysis was performed using the Kaplan-Meier method and multivariable Cox proportional regression.

RESULTS

High initial SUVmax was significantly associated with advanced Ann-Arbor stage (p = 0.0352), elevated LDH levels (p = 0.0059) and plasma EBV DNA detection (p = 0.0278). SUVmax correlated with worse progression-free survival (PFS) (HR 3.68, 95% CI 1.56-8.69, p = 0.0030) and a trend toward worse overall survival (OS) (HR 2.06, 95% CI 0.95-4.45, p = 0.0676). End of treatment Deauville scores of 4-5, as compared to scores of 1-3, was associated with worse PFS (HR 2.72, 95% CI 1.04-7.12, p = 0.0419). Notably, while all patients with scores of 5 developed progressive disease, only 2 of 5 patients with scores of 4 eventually relapsed. Clinical indices (NABS score) were still able to stratify survival outcomes regardless of end-of-treatment Deauville scores.

CONCLUSIONS

A Deauville score of 5 is more diagnostic of true disease progression than a score of 4, and NABS score may be used in patients who achieve Deauville scores of 1-3 for further risk stratification. A higher SUVmax at baseline portends a worse prognosis in NKTCL.

Assessment of the prognostic value of interim fluorodeoxyglucose positron emission tomography/computed tomography in nasal-type extranodal natural killer/T-cell lymphoma

Background

The prognostic value of interim positron emission tomography/computed tomography (PET/CT) for nasal-type extranodal natural killer/T-cell lymphoma (ENKTL) is controversial. We evaluated the prognostic value of interim PET/CT in ENKTL patients to facilitate risk stratification and guide clinical treatment.

Methods

Patients with ENKTL who received first-line chemotherapy based on L-asparaginase/pegaspargase with/without involved-field radiotherapy were recruited for this study. Pretreatment and interim PET/CT evaluations were performed. Interim PET/CT was evaluated via the maximum standardized uptake value (SUVmax) and the Deauville 5-point scale (DS); and the capacity to predict progression-free survival (PFS) and overall survival (OS) was evaluated. Receiver operating characteristic (ROC) curves were used to determine the optimal SUVmax cutoff. Fisher's exact test was used to analyze relationships between interim PET/CT results and clinical characteristics. Univariate and multivariate analyses were performed to examine the independent effects of interim PET/CT. The Cochran-Mantel-Haenszel test was used to assess the prognostic value of interim PET/CT at different timepoints.

Results

Overall, 129 ENKTL patients were enrolled. The optimal interim PET/CT SUVmax cut-off was 4.95. The median follow-up was 34 [2-90] months, in the low SUVmax group (≤4.95), the 2-year PFS and OS rates were 76.3% and 88.0%, respectively; in the high SUVmax group (>4.95), the PFS and OS rates were 15.6% and 44.5%, respectively. Likewise, for the DS 1-3 group, the PFS and OS rates were 78.9% and 91.2%, respectively; and in the DS 4 or 5 group, the rates of PFS and OS were 49.7% and 69.0%, respectively. In univariate analysis, interim PET/CT evaluation based on SUVmax and DS scores were both PFS and OS predictors. In multivariate analysis, SUVmax was independently significantly associated with PFS (P<0.001) and OS (P=0.002), and DS was independently significantly associated with PFS (P=0.004) but not OS (P=0.204). In the Cochran-Mantel-Haenszel testing, the SUVmax and DS were significantly associated with PFS and OS after adjustments for the interim PET/CT timing.

Conclusions

Interim PET/CT was of prognostic value concerning ENKTL. The SUVmax is an independent prognostic indicator of PFS and OS, while the DS is an independent prognostic indicator of PFS but not OS. The SUVmax is of greater prognostic value than DS.

Nomograms based on SUVmax of 18F-FDG PET/CT and clinical parameters for predicting progression-free and overall survival in patients with newly diagnosed extranodal natural killer/T-cell lymphoma

BACKGROUND

The prognostic value of 18F-FDG PET/CT in extranodal natural killer/T-cell lymphoma (ENKTL) is not well established. We aimed to develop nomograms for individualized estimates of progression-free survival (PFS) and overall survival (OS) in patients with ENKTL using 18F-FDG PET/CT parameters and clinical parameters.

METHODS

A total of 171 patients with newly diagnosed ENKTL undergoing 18F-FDG PET/CT scanning were retrospectively analyzed. Nomograms were constructed according to multivariate Cox proportional hazards regression. The predictive and discriminatory capacities of the nomograms were then measured using the concordance index (C-index), calibration plots, and Kaplan-Meier curves. The C-index, the area under receiver operating characteristic (ROC) curve (AUC), and decision curve analysis (DCA) were used to contrast the predictive and discriminatory capacities of the nomograms against with the International Prognostic Index (IPI) and Korean Prognostic Index (KPI).

RESULTS

Multivariate analysis demonstrated that pretreatment SUVmax≥9.5, disease stage II and III-IV, elevated lactate dehydrogenase (LDH), and elevated β2-microglobulin (β2-MG) had the strongest association with unfavorable PFS and OS. In addition, hemoglobin (Hb) < 120 g/L had a tendency to be associated with PFS. Both nomogram models incorporated SUVmax, Ann Arbor stage, LDH, and β2-MG. The PFS nomogram also included Hb. The nomograms showed good prediction accuracies, with the C-indexes for PFS and OS were 0.729 and 0.736, respectively. The calibration plots for 3-year and 5-year PFS/OS reported good consistency between predicted and observed probabilities for survival time. The PFS and OS were significantly different according to tertiles of nomogram scores (p < 0.001). The C-index and AUCs of the nomograms were higher than that of IPI and KPI. Moreover, DCA showed that the predictive accuracy of the nomograms for PFS and OS were both higher than that of IPI and KPI.

CONCLUSIONS

This study established nomograms that incorporate pretreatment SUVmax and clinical parameters, which could be effective tools for individualized prognostication of both PFS and OS in patients with newly diagnosed ENKTL.

Baseline SUVmax of 18F-FDG PET-CT indicates prognosis of extranodal natural killer/T-cell lymphoma

To evaluate the prognostic value of the baseline SUVmax of F-FDG PET-CT in extranodal natural killer/T-cell lymphoma (NKTCL) patients.From January 2010 to December 2015, 141 extranodal NKTCL patients with staging F-FDG PET-CT scan were divided into two group based on SUVmax cutoff value obtained from operating characteristic (ROC) curves. All the patients received radiotherapy, chemotherapy or chemoradiation. Survival analysis was performed on the basis of SUVmax.The median baseline SUVmax of the tumors was 11.67 (range 2.6-34.6). The ROC curves showed that the optimal cutoff of the baseline SUVmax was 9.65. The patients were divided into two groups: low SUV group (SUVmax < 9.65) and high SUV group (SUVmax ≥ 9.65). Patients in high SUV group were more likely to have invasive disease outside the nasal cavity (P < .001), poorer ECOG scores (P = .012) and higher LDH levels (P = .034). The univariate survival analyses indicated that high SUVmax was a poor prognostic factor for overall survival (OS, P = .038), progression free survival (PFS, P = .006) and distant relapse free survival (DRFS, P = .001), but not for local recurrence free survival (LRFS, P > .05). These results were consistent with that of the survival analyses using the Kaplan-Meier method. The multivariate survival analyses showed that the baseline SUVmax was no longer a prognostic factor for OS (HR 1.99, 95% CI 0.81-4.88, P = .135), but it still indicated worse PFS (HR 2.6, 95% CI 1.24-5.46, P = .012) and DRFS (HR 4.58, 95% CI 1.83-11.46, P = .001) independent of other variables.For extranodal NKTCL patients, a higher baseline SUVmax of F-FDG PET-CT was associated with more aggressive clinical features. An SUVmax ≥ 9.65 was an independent poor prognostic factor for DRFS and PFS. Thus, the baseline SUVmax may be a valuable tool to help identify patients with a high risk of disease progression.

Positron emission tomography/computed tomography in the diagnosis, staging, and prognostic evaluation of natural killer/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTL) is a rare subtype of non-Hodgkin's lymphoma that is associated with Epstein-Barr virus infection. The clinicopathological features of NKTL are unique among lymphomas. NKTL is an aggressive disease with a poor prognosis in the absence of effective treatment. Accurate diagnosis and staging are essential to ensure an appropriate treatment strategy and accurate prognosis of NKTL. ¹⁸F-Fluorodexoyglucose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is a valuable technique in the diagnosis, staging, and prognostic evaluation of various types of malignant tumors, including NKTL. PET/CT imaging studies of patients with NKTL have shown that NKTL is ¹⁸F-FDG-avid and that PET/CT is superior to conventional methods in detecting cutaneous and extracutaneous lesions. We herein review recent PET/CT studies that have provided considerable insight into the diagnosis, staging, prognostic evaluation, and treatment effectiveness in patients with NKTL.

Prognostic value of baseline, interim and end-of-treatment 18F-FDG PET/CT parameters in extranodal natural killer/T-cell lymphoma: A meta-analysis

METHODS

We searched the PubMed, EMBASE, Cochrane Library and Medline databases for eligible articles. SUVmax, MTV, and TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT were regarded as efficacy data. Combined hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were estimated using RevMan 5.3 software.

RESULTS

Nine trials with a total of 535 ENKTL patients were included. SUVmax, MTV and TLG on B-PET/CT were significantly associated with PFS with HRs of 2.78 (95%CI 1.54-5.03), 3.61 (95%CI 1.96-6.65) and 5.62 (95%CI 1.94-16.33), respectively, and with OS with HRs of 4.78 (95%CI 2.29-9.96), 3.20 (95%CI 1.55-6.60) and 7.76 (95%CI 1.79-33.58), respectively. For the DS on I-PET/CT, the HRs for PFS and OS were 5.15 (95%CI 2.71-9.80) and 5.80 (95%CI 2.28-14.73), respectively. Similarly, the DS on E-PET/CT was a significant predictor of PFS and OS with HRs of 3.65 (95%CI 2.13-6.26) and 3.32 (95%CI 1.79-6.15), respectively.

CONCLUSION

Our results suggest that SUVmax, MTV, TLG on B-PET/CT, DS on I-PET/CT and DS on E-PET/CT may be significant prognostic indicators for PFS and OS in ENKTL patients. Moreover, TLG tends to be superior to SUVmax and MTV on B-PET/CT for predicting survival of ENKTL patients. Therefore, response monitoring and prognostication assessments based on multiple PET/CT parameters should be considered in the management of ENKTL patients.