Results of a retrospective study of patients with follicular lymphoma treated with chemoimmunotherapy showed 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) assessed at the end-of-induction therapy (EOI) was an independent predictor of disease progression. The findings from this study were published in the journal of Nuclear Medicine and Molecular Imaging.
Although FDG PET/CT is considered to be the standard procedure for staging and response assessment in Hodgkin lymphoma and most types of FDG-avid subtypes of non-Hodgkin lymphoma, its prognostic value in follicular lymphoma has not been verified.
This study included 33 patients with newly diagnosed follicular lymphoma treated with rituximab-based chemoimmunotherapy who had undergone PET/CT imaging scans at baseline, EOI, as well as at an interim point.
The 5-point Deauville criteria (ie, 1 – no update; 2 – uptake less than or equal to that of the mediastinum; 3 – uptake greater than the mediastinum but less than the liver; 4 – uptake moderately more than the liver; 5 – uptake markedly more than the liver or by new sites of disease) was used to interpret the results of PET/CT imaging. Patients with scores of 1, 2, or 3 were classified as PET-negative, whereas those with scores of 4 or 5 were considered to be PET-positive.
At a median follow-up of 41.6 months, the median progression-free survival (PFS) for the overall cohort was 38.8 months. At an interim assessment point, median PFS was significantly longer for PET-negative compared with PET-positive patients (55.5 months versus 39.9 months; P =.005). This difference in median PFS was even more marked when PET-negative and PET-positive patients were compared at EOI (60.5 months versus 14.2 months; P <.001). On multivariate analysis, only PET status at EOI was found to be an independent predictor of disease progression (P =.014).
Limitations of the study mentioned by the study authors included the small sample size, as well as the short follow-up, which precluded an assessment of the prognostic value of PET/CT with respect to overall survival.
In their concluding remarks, the study authors commented that “further studies are required to identify how changing treatment strategy in PET (interim)- or PET (EOI)-positive could improve outcome in follicular lymphoma.”
Boo SH, O JH, Kwon SJ, et al. Predictive value of interim and end-of-therapy 18F-FDG PET/CT in patients with follicular lymphoma. Nucl Med Mol Imaging. 2019;53(4):263-269.