Abstract
1607
Objectives Non-Hodgkin’s lymphomas arising from the tissues other than primary lymphatic organs (lymph nodes, bone marrow, spleen, thymus and Waldeyer’s ring of pharyngeal lymphatics) are called primary extranodal lymphoma. Although it can be seen in almost every organ, gastrointestinal tract is the most frequently involved localization. Its incidence is around 30-40% of all extranodal cases in hospital and population-based series published thus far. They have different etiopathogenesis, genetic origin, biologic features, clinical characteristics and outcome. We aimed to evaluate the prognostic value of metabolic tumor parameters derived from initial FDG-PET/CT in patients with a medley of primary extranodal lymphoma in this study.
Methods In this retrospective cohort study conducted between 2004 and 2015, there are 67 patients with primary extranodal lymphoma for whom FDG-PET/CT was requested for primary staging. Quantitative PET/CT parameters (maximum standardized uptake value (SUVmax), average standardized uptake value(SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG)) were used to estimate disease-free survival and overall survival.
Results SUVmean, MTV and TLG were found statistically significant after multivariate analysis. SUVmean remained significant after ROC curve analysis. 1 unit increment of SUVmean amplifies recurrence rate 1.4 times. Sensitivity and specificity were calculated as 88% and 64%, respectively when the cut-off value of SUVmean was chosen as 5.15. After the investigation of primary presentation sites and histopathological variants according to recurrence, there is no difference amongst the variants. But primary site (organ) of extranodal lymphomas is statistically important (p=0.014). Testis and central nervous system (CNS) lymphomas has higher recurrence rate (62.5%, 73%, respectively).
Conclusions High SUVmean, MTV and TLG values obtained from primary staging FDG-PET/CT are potential risk factors for both disease-free survival and overall survival in primary extranodal lymphoma. SUVmean is the most significant one amongst them for estimating recurrence/metastasis. Testis and CNS lymphomas has higher recurrence rate than other sites.