Does PET/CT scanning during chemotherapy improve IPI-based outcome predictions for DLBCL patients?

This study investigated whether interim FDG PET/CT scanning during chemotherapy helps predict risk for new DLBCL (diffuse large B-cell lymphoma) patients. This study concluded that this scanning improves the risk classifications used to predict outcomes for DLBCL patients.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma (NHL), accounting for about 30% of new NHL cases in the U.S. The most widely used treatment for this aggressive cancer is R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). However, only 60% of DLBCL patients experience remission after this treatment. Because DLBCLs are a diverse group of cancers, it is difficult to accurately determine prognosis or risk.

The standard International Prognostic Index (S-IPI) is the most widely used tool for predicting prognosis. The revised (R-IPI) and enhanced (NCCN-IPI) versions of the IPI scale are also used. These tools predict a patient’s prognosis before chemotherapy.

FDG PET/CT scanning during chemotherapy treatment (interim) is used to evaluate how well a patient responds to treatment. This scanning was shown to accurately predict patient outcomes when done at four chemotherapy cycles. Whether this scanning can improve risk classification by the IPI scale is under investigation.

This study involved 185 patients with DLBCL at various stages: 12.4% (stage 1), 20.6% (stage 2), 14.6% (stage 3), and 52.4% (stage 4). All patients received R-CHOP-like chemotherapy, and FDG PET/CT scanning after four chemotherapy cycles. The average follow-up period was 44 months.

At follow-up, the progression-free survival (time from treatment before disease progression) rate was 47.6%. The overall survival (time from treatment until death from any cause) rate was 67%. The progression-free survival rate at 2 years was 60%. The overall survival rate at 2 years was 81%.

Patients with positive PET/CT scans had a 2-year progression-free survival rate of 23% and a 2-year overall survival rate of 55%. Patients with negative PET/CT scans had a 2-year progression-free survival rate of 82% and a 2-year overall survival rate of 96%.

The different IPI risk groups with positive PET scan results also showed lower survival rates. S-IPI low-risk patients with positive PET results had significantly lower progression-free survival (31%) and overall survival rates (65%) than low-risk patients with negative PET results (PFS 88% and OS 98%). R-IPI poor-risk patients with positive PET results had significantly lower progression-free survival (18%) and overall survival rates (48%) than good-risk patients (PFS 26% and OS 63%). NCCN-IPI high-risk patients with positive PET results had significantly lower progression-free survival (20%) and overall survival rates (51%) than low-risk patients (PFS 22% and OS 60%).

This study concluded that interim FDG PET/CT scanning helps to better classify risk for DLBCL patients, especially for low and high-risk patients.

This study looked back in time to analyze data. As a result, the collected data may be incomplete. The number of patients with positive PET scan results was also small. More studies are needed to confirm the results with larger populations of DLBCL patients.

If you have been recently diagnosed with DLBCL, talk to your care team about getting a PET/CT scan after your fourth chemotherapy cycle to guide your treatment plan.