Paediatric non Hodgkin’s lymphoma: Prognostic value of early interim FDG PET/CT done after two cycles of chemotherapy

Objectives Paediatric Non Hodgkin’s lymphomas (NHL) respond well to chemotherapy. In non responders early bone marrow transplant (BMT) is curative. Risk adapted treatment strategies are being evaluated for management of paediatric lymphoma. The present prospective study was aimed to evaluate the prognostic significance of early interim PET/CT done after 2 cycles of chemotherapy in paediatric NHL patients.

Methods Thirty one patients (27 male and 4 female) patients with mean age of 10yrs (median-10; range: 4-15) with histologically proven NHL were evaluated. Histologically it was anaplastic large cell lymphoma in 4, T cell lymphoma in 2 and B cell lymphoma in 25 patients. At diagnosis 2 patients were in stage I, 1 in stage II, 16 in stage III and 12 in stage IV. FDG PET/CT was done at diagnosis, after 2 cycles of chemotherapy and at the end of therapy. PET/CT findings were correlated with CECT, bone marrow biopsy and clinical findings.

Results Early interim PET/CT after 2 cycles of chemotherapy (PET/CT-2) was positive in 16 (51.6 %) patients and negative in 15 (49.4 %). Of total 31 patients, 21 showed complete remission (CR), 1 showed partial remission (PR), 1 had stable disease (SD) and 8 had progressive disease (PD) at end of therapy. Among these 9 patients who had SD and PD, 7 (77.7%) had positive PET/CT-2 and 2 (22.3%) had negative PET/CT-2.There was significant difference in overall survival (OS) of patients with positive and negative PET/CT-2(p<0.028). PET/CT after 2 cycles has sensitivity of 88.8%, specificity of 63.6%, PPV of 50%, NPV of 93.3% and accuracy of 70.9% for predicting final outcome.

Conclusions Early FDG PET/CT after 2 cycles can accurately prognosticate paediatric NHL patients and may be crucial to for planning risk adapted treatment strategy