Metabolic phenotypes of lymphomas relate to the rates of treatment response

Abstract

Objectives : To investigate the relationship of metabolic phenotype measured by staging PET and the time interval for first metabolic remission of lymphomas. Methods : 66 patients with newly diagnosed non-Hodgkin’s lymphoma (NHL) and Hodgkin’s disease (HD) but without diabetes and other malignancies who had F-18 FDG PET scan performed within 3 months of biopsy were included. Lymphomas were classified using the WHO criteria and graded by the metabolic activity of initial staging PET using maximum standard uptake value (SUV) over the area of biopsy. Cox regression was performed for the duration of post-treatment PET against status of negative PET (otherwise censored) with age, sex, pathologic grade and SUV from staging pre-treatment PET as covariates. Kaplan Meier analysis of the probability of the interval for first negative post-treatment PET was performed in patients with a best discriminating SUV. All PET scans were obtained one hour after injection of 370 MBq F-18 FDG after the patients fasted about 4 hours using a dedicated whole body PET scans. Results : The mean interval of the first post-treatment PET was performed after a duration of 198+/-153 days of the first staging PET scan. Cox regression analysis suggested that SUV=7.5 stratified the differences in the probability in the interval of the first metabolic remission or negative post-treatment PET. Using this cut-off value SUV, there was a difference in the remission interval as revealed by the first negative PET scans among various lymphomas (p=0.02). Conclusions : Results suggest that high metabolic phenotype lymphomas by initial staging PET would respond more quickly to treatment as measured by post-treatment PET than those with low metabolic phenotype lymphomas. As there is a high rate of recurrence in NHL, this may impact decision for the follow up interval of lymphomas.