Prognostic Value of 18F-FDG PET/CT Radiomics in Extranodal Nasal-Type NK/T Cell Lymphoma

OBJECTIVE

To investigate the prognostic utility of radiomics features extracted from 18F-fluorodeoxyglucose (FDG) PET/CT combined with clinical factors and metabolic parameters in predicting progression-free survival (PFS) and overall survival (OS) in individuals diagnosed with extranodal nasal-type NK/T cell lymphoma (ENKTCL).

MATERIALS AND METHODS

A total of 126 adults with ENKTCL who underwent 18F-FDG PET/CT examination before treatment were retrospectively included and randomly divided into training (n = 88) and validation cohorts (n = 38) at a ratio of 7:3. Least absolute shrinkage and selection operation Cox regression analysis was used to select the best radiomics features and calculate each patient's radiomics scores (RadPFS and RadOS). Kaplan-Meier curve and Log-rank test were used to compare survival between patient groups risk-stratified by the radiomics scores. Various models to predict PFS and OS were constructed, including clinical, metabolic, clinical + metabolic, and clinical + metabolic + radiomics models. The discriminative ability of each model was evaluated using Harrell's C index. The performance of each model in predicting PFS and OS for 1-, 3-, and 5-years was evaluated using the time-dependent receiver operating characteristic (ROC) curve.

RESULTS

Kaplan-Meier curve analysis demonstrated that the radiomics scores effectively identified high- and low-risk patients (all P < 0.05). Multivariable Cox analysis showed that the Ann Arbor stage, maximum standardized uptake value (SUVmax), and RadPFS were independent risk factors associated with PFS. Further, β2-microglobulin, Eastern Cooperative Oncology Group performance status score, SUVmax, and RadOS were independent risk factors for OS. The clinical + metabolic + radiomics model exhibited the greatest discriminative ability for both PFS (Harrell's C-index: 0.805 in the validation cohort) and OS (Harrell's C-index: 0.833 in the validation cohort). The time-dependent ROC analysis indicated that the clinical + metabolic + radiomics model had the best predictive performance.

CONCLUSION

The PET/CT-based clinical + metabolic + radiomics model can enhance prognostication among patients with ENKTCL and may be a non-invasive and efficient risk stratification tool for clinical practice.

Risk stratification and prognostic value of multi-modal MRI-based radiomics for extranodal nasal-type NK/T-cell lymphoma

BACKGROUND

Magnetic resonance imaging (MRI) performs well in the locoregional assessment of extranodal nasal-type NK/T-cell lymphoma (ENKTCL). It's important to assess the value of multi-modal MRI-based radiomics for estimating overall survival (OS) in patients with ENKTCL.

METHODS

Patients with ENKTCL in a prospectively cohort were systemically reviewed and all the pretreatment MRI were acquisitioned. An unsupervised spectral clustering method was used to identify risk groups of patients and radiomic features. A nomogram-revised risk index (NRI) plus MRI radiomics signature (NRI-M) was developed, and compared with the NRI.

RESULTS

The 2 distinct type I and II groups of the MRI radiomics signatures were identified. The 5-year OS rates between the type I and type II groups were 87.2% versus 67.3% (P = 0.002) in all patients, and 88.8% versus 69.2% (P = 0.003) in early-stage patients. The discrimination and calibration of the NRI-M for OS prediction demonstrated a better performance than that of either MRI radiomics or NRI, with a mean area under curve (AUC) of 0.748 and 0.717 for predicting the 5-year OS in all-stages and early-stage patients.

CONCLUSIONS

The NRI-M model has good performance for predicting the prognosis of ENKTCL and may help design clinical trials and improve clinical decision making.

[Outcome of radiotherapy for low-risk early-stage patients with extranodal NK/T-cell lymphoma, nasal-type]

Objective: To evaluate the prognosis and determine the failure patterns after radiotherapy for low-risk early-stage patients with extranodal NK/T-cell lymphoma, nasal-type (ENKTCL). Methods: A total of 557 patients from 2000-2015 with low-risk early-stage ENKTCL who received radiotherapy (RT) with or without chemotherapy (CT) from China Lymphoma Collaborative Group were retrospectively reviewed. Among them, 427 patients received combined modality therapy, whereas 130 patients received RT alone. Survivals were calculated by Kaplan-Meier method and compared with Log-rank test. Overall survival (OS) was compared with age and sex-matched general Chinese population using expected survival and standardized mortality ratio (SMR). Cox stepwise regression model was used for multivariate analysis. Results: The 5-year OS and progression-free survival (PFS) were 87.2% and 77.2%. The SMR was 3.59 (P<0.001) at 1 year after treatment, whereas it was 1.50 at 4 years after treatment, without significant difference between ENKTCL group and country-matched general population (P=0.146). Compared with RT alone, CMT did not result in significantly superior 5-year OS (87.0% vs 87.4%, P=0.961) or PFS (76.1% vs 80.7%, P=0.129). Local failure (11.5%, 64/557) and distant failure (10.8%, 60/557) were the main failure modes, while regional failure was rare (2.9%, 16/557). The 5-year locoregional control rate (LRC) was 87.2% for the whole group, with 89.5% for ≥50 Gy versus 73.7% for <50 Gy (P<0.001). Radiotherapy dose was an independent factor affecting LRC(P<0.05). Conclusions: Radiotherapy achieves a favorable prognosis in patients with low-risk early-stage ENKTCL. The incidence of either locoregional or distant failure is low. Radiation dose still is an important prognostic factor for LRC.