Prognostic value of maximum standard uptake value on pretreatment ¹⁸F-FDG PET-CT in newly diagnosed extranodal natural killer/T-cell lymphoma

Objective: To determine the prognostic value of maximum standard uptake value (SUVmax) on pretreatment ¹⁸F-FDG PET-CT scan in patients with newly diagnosed extranodal natural killer/T cell lymphoma (ENKL). Methods: The clinical information of 44 patients with ENKL undergoing ¹⁸F-FDG PET-CT scan before treatment were analyzed retrospectively. SUVmax on PET-CT were evaluated by SPSS 17.0 for the associations with prognostic factors, treatment efficacy and survival time. Results: The median SUVmax was significantly higher (Z = -2.660, P = 0.008) in patients with B symptoms (14.8 [3.9-25.7]) than that without B symptoms (9.0 [5.0-18.6]). The SUVmax of patients with hemophagocytic syndrome (15.7 [8.4-25.7]) was also significantly higher (Z = -2.464, P = 0.014) than that without (11.0 [3.9-25.2]). There was no significant difference between patients with and without Epstein-Barr virus infection (Z = -1.171, P=0.242). The SUVmax was positively associated with patient characteristics including Korean prognostic index (r = 0.470, P = 0.001), stage (r = 0.449, P = 0.002), Ki-67 (r = 0.476, P = 0.001), lactate dehydrogenase (r = 0.394, P = 0.010) and β2-microglobulin level (r = 0.398, P = 0.010). The SUVmax was inversely associated with white blood cell count (r = -0.328, P = 0.034) and lymphocyte count (r = -0.315, P = 0.042). There was no association between SUVmax and age, hemoglobin content and platelet count (P > 0.05). The SUVmax was significantly different between complete and incomplete remission (Z = -3.160, P = 0.002), between patients with and without treatment efficacy (Z = -2.998, P = 0.003). The complete remission, overall response and 2-year overall survival rates were significantly different between patients with SUVmax below and above 12.75 (P < 0.05). Conclusion: The SUVmax on pretreatment ¹⁸F-FDG PET-CT in patients with ENKL is well correlated with other prognostic factors and it can be used to predict the prognosis. (authors)