Early evaluation of tumor response to 90Y-ibritumomab radioimmunotherapy in relapsed/refractory B cell non-Hodgkin lymphoma: what is the optimal timing for FDG-PET/CT?

Prognostic value of 18F-FDG PET/CT in T-Lymphoblastic lymphoma before and after hematopoietic stem cell transplantation

PURPOSE

We aimed to evaluate the prognostic value of ¹⁸F-FDG PET/CT in patients with relapsed or refractory T-Lymphoblastic lymphoma (T-LBL) undergoing hematopoietic stem cell transplantation (HSCT).

METHODS

PET/CT was performed in 21 consecutive relapsed or refractory T-LBL patients scheduled for HSCT. All PET/CT images were assessed using the Deauville criteria, and patients were divided into negative (Deauville ≤ 3) and positive (Deauville > 3) groups for comparison. The predictive value of sex, age, Ann Arbor stage, presence of B symptoms, lactate dehydrogenase level, presence of extranodal disease, and PET/CT results before and after HSCT were evaluated.

RESULTS

Kaplan-Meier analysis showed that only PET/CT after HSCT (post-PET) was correlated with progression-free survival (PFS) (P = 0.030). The Cox regression model also showed that the post-PET-positive group had a higher hazard ratio (HR) than the negative group (HR = 3.884 and P = 0.049). However, none of the evaluated factors were predictive of overall survival (OS).

CONCLUSIONS

Pre-PET cannot predict the PFS and OS of patients with T-LBL undergoing HSCT, which means that ¹⁸F-FDG PET/CT cannot be used for identifying patients who can benefit from HSCT. Post-PET is not predictive for OS in patients with T-LBL undergoing HSCT. However, post-PET showed strong correlations with PFS, which means that it may be useful for guiding subsequent clinical treatment decisions.

Interim response in diffuse large B cell lymphoma on CT: what is the optimal size reduction (ΔSPD) for predicting outcome?

OBJECTIVES

To investigate whether there was an optimal interim size reduction (iΔSPD) cutoff value that could discriminate diffuse large B cell lymphoma (DLBCL) patients with poor prognosis.

METHODS

This retrospective study enrolled 265 newly diagnosed DLBCL patients with baseline and interim (after 3 cycles) contrast-enhanced computed tomographic scan (CECT) available. Two radiologists evaluated CECT images and selected target lesions according to the Lugano Response Criteria. Lymph nodes greater than 15 mm in longest diameter (LDi) and extra-nodal lesions with LDi greater than 10 mm could be chosen as target lesions and used to calculate iΔSPD. A software tool, X-Tile, was used to calculate the optimal iΔSPD cutoff value to differentiate patients with good vs. poor prognosis. Receiver operating characteristic curve analysis, Cox regression analysis, and Kaplan-Meier analyses were further used to validate the optimal cutoff value.

RESULTS

The optimal cutoff value of iΔSPD calculated by X-tile was 80%. Compared with 50% and 100%, 80% cutoff value had the intermediate sensitivity and specificity (57.75% and 86.69% for overall survival (OS), 48.98% and 92.22% for progression-free survival (PFS), respectively), but the maximal Youden index (0.4744 for OS, 0.4120 for PFS, respectively) and areas under the curve (0.737 [0.680, 0.789] for OS). Cox regression analysis also revealed that iΔSPD < 80% could independently predict an inferior OS and PFS (both p < 0.001) while neither iΔSPD < 50% nor iΔSPD = 100% could.

CONCLUSIONS

iΔSPD with the cutoff value 80% is an independent predictor of PFS and OS for patients with DLBCL. Results suggest that treatment should be modified for patients with iΔSPD < 80%.

KEY POINTS

• The aim of interim response assessment is to identify patients whose disease has not responded to or has progressed on induction therapy. • A cutoff value of 80% in size reduction (ΔSPD) is an independent predictor of PFS and OS for DLBCL patients and is better than 50%. • In DLBCL patients with interim ΔSPD < 80%, a change to a more efficient therapy should be considered.