OBJECTIVETo evaluate the value of (18)F-FDG PET/CT in detecting residual disease and predicting relapse following first-line treatment in patients with diffuse large B cell lymphoma (DLBCL).

METHODSThe clinical data of 39 patients with DLBCL, who underwent PET/CT scan after first-line treatment, were analyzed retrospectively. Kaplan-Meier method was used to analyze the survival of patients.

RESULTSPET/CT findings were interpreted as negative, mild metabolism and positive. Seventeen patients' PET/CT findings were judged as negative, none of them relapsed with a median follow-up of 24.1 months, 13 were judged as mild metabolism, 2 of them relapsed with a median follow-up of 17.1 months. Of the rest 9 findings were judged as positive with a median follow-up of 16.3 months, 4 patients were considered as disease progression according to clinical manifestations and other radiographic results, 2 patients relapsed at the time points of 13.5 and 6.8 months after PET/CT scan respectively, the other 3 patients were diagnosed as negative by biopsy, none of them relapsed at the time points of 5.9, 9.6 and 20.0 months after PET/CT scan respectively. One-year progression-free-survival (PFS) for negative, mild metabolism and positive groups was 100%, 83% and 56%, respectively. Two-year PFS was 100%, 83% and 42%, respectively. Overall survival (OS) at 1 year for negative, mild metabolism and positive groups was 100%, 100% and 89%, respectively. Two-year OS was 100%, 100% and 63%, respectively (P = 0.004).

CONCLUSIONDLBCL patients with negative and mild metabolism PET/CT following first-line treatment had good prognosis, who needed no additional therapy. While patients with positive PET/CT had poor prognosis, those patients should receive biopsy before adjusting treatment regimen because of the high false-positive rate.