Prognostic Significance Of Positron Emission Tomography-Computed Tomography In Patients With Marginal Zone Lymphoma
Authors: Suh Cheolwon , Park Ji Hyun , Yoon Dok Hyun , Huh Jooryung , Ryu Jin Sook , Park Chan-Sik 
Published: October 2019

Abstract

Background & Aims
18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) scan has been increasingly used for initial staging and response evaluation in patients with lymphomas, and its clinical utility is well established in Hodgkin’s lymphoma (HL) as well as in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). However, its role remains undetermined in marginal zone lymphomas (MZL), due to its relatively low FDG avidity as well as small numbers of patients in the Western countries although it is the most common type of indolent lymphoma in Korea. Thus, we aimed to assess the prognostic significance of PET-CT scan performed after first-line therapy in patients with MZL.

Patients & Methods
We retrospectively reviewed the medical records of a total of 194 patients with pathologically confirmed MZL in the Asan Medical Center between February 2003 and February 2011. Post-treatment FDG PET-CT scan was defined as which performed during the periods of 2 to 4 weeks after the completion of chemotherapy or 7 to 9 weeks after radiotherapy. Among them, we identified 32 patients with evaluable pretreatment, interim and post-treatment PET-CT scans who received chemotherapy. We investigated the prognostic significance of maximum standardized uptake value (SUVmax) at pretreatment PET-CT and metabolic complete response (mCR) at post-treatment PET-CT. The log-rank test was used to assess the correlation of event-free survival (EFS) and overall survival (OS) with baseline SUVmax or the presence of mCR. All categorical variables were analyzed using Chi-square test or Fisher’s exact test.

Results
In a total of analyzable 32 patients, histopathologic subtypes of them were as follow: Mucosa-associated lymphoid tissue (MALT) lymphoma (n=14, 43.8%), nodal MZL (n=17, 53.1%), and splenic MZL (n=1, 3.2%). The median SUVmax in pretreatment PET-CT was 5.3 (range, 1.3 – 18.8). There were no significant associations of SUVmax (cutoff: 5.3) at pretreatment PET-CT to mCR in both post-treatment and interim PET-CT scans (p =0.694 and p=0.723, respectively). However, high SUV group (SUVmax at baseline PET-CT >5.3) showed inferior 5-year EFS and OS to low SUV group (¡Â 5.3) with marginal statistical significicance (p=-0.072 and p=0.101, respectively). With a median follow-up duration of 41 months (range, 9 to 99 months), 5-year OS and EFS rate were 87.9% and 43.9%, respectively. 5-year EFS was significantly superior in patients who attained mCR at post-treatment PET-CT (p =0.010, 55.0% to 0%), and also in interim PET-CT (p=0.007, 70.6% to 13.1%). In addition, patients who attained early mCR showed significantly better 5-year EFS than patients of delayed and never mCR groups (p=0.011, 70.6% to 22.5%, and 0%).

Conclusion
In our study cohort, patients with low SUVmax (¡Â 5.3) in pretreatment PET-CT showed strong trends of superior EFS and OS. More importantly, early attained mCR and mCR at post-treatment PET-CT were independent predictors of higher 5-year EFS rates.

Disclosures:
No relevant conflicts of interest to declare.