Prognostic value of positron emission tomography in the evaluation of post‐treatment residual mass in patients with Hodgkin's disease and non‐Hodgkin's lymphoma

The prognostic value of 18F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) in the assessment of post‐treatment residual masses in patients with Hodgkin's disease (HD) or non‐Hodgkin's lymphomas (NHL) was evaluated. We prospectively studied 58 patients with HD (n = 43) or NHL (n = 15) who had post‐therapeutic complete remission with residual masses (CRu) indicated by computerized tomography. Analysis of 62 residual locations by FDG‐PET was performed separately for HD and NHL. Patients with a PET‐positive residual mass [standardized uptake value (SUV) > 3] had a recurrence rate of 62·5% (5/8 patients), whereas patients with PET‐negative residual mass (SUV ≤ 3·0) showed a recurrence rate of 4% (2/50 patients, P = 0·004). A positive FDG‐PET study correlated with a significantly poorer progression‐free survival (P < 0·00001). No recurrence occurred in any of the 39 HD patients with a negative PET scan (negative predictive value, 100%). Four out of four NHL patients with a positive PET study relapsed (positive predictive value, 100%). In conclusion, FDG‐PET is a suitable non‐invasive method with a high degree of accuracy in the prediction of early recurrence in lymphoma patients with CRu.