Increased glucose metabolism in untreated non-Hodgkin's lymphoma: a study with positron emission tomography and fluorine-18-fluorodeoxyglucose.

Glucose metabolism has been shown to be increased in neoplastic tissue. It has been suggested that high activity of glucose metabolism is associated with a high grade of malignancy of human cancer. We studied in vivo glucose metabolism in 22 patients with untreated non-Hodgkin's lymphoma with fluorine-18-fluorodeoxyglucose (FDG) and positron emission tomography (PET). FDG uptake in lymphoma deposits was measured blinded to clinical data, and compared with histologic classification and proliferative activity. Tracer uptake was measured by using two indices of FDG accumulation: the standardized uptake value (SUV) and the regional metabolic rate (rMR) for the tracer. The median SUV of the lymphomas was 8.5 (range, 3.5 to 31.0), and the median rMR 22.7 mumol/100 g/min (range, 9.0 to 124.3 mumol/100 g/min). A high FDG uptake in tumors was associated with high histologic degree of malignancy as defined by the Working Formulation (P = .005 for the SUV, and P = .04 for the rMR) or by the Kiel classification (P = .003 for the SUV, and P = .02 for the rMR). A high FDG accumulation was also associated with a high S-phase fraction (r = .786 for the SUV, P = .0002; and r = .774 for the rMR, P = .02). We conclude that in untreated non-Hodgkin's lymphomas high FDG uptake is associated with high histologic grade of malignancy and a high proliferation rate. This minimally invasive method may find application in assessing lymphoma lesions in patients who are poor candidates for surgery, and it may provide further information in cases where the grade of aggressiveness of lymphoma is not settled based on clinical or histologic data.