In the study, we aimed to characterize the role of FDG PET/CT surveillance at 12 months of malignant lymphoma in asymptomatic patients after a first complete remission and to define a rational follow-up strategy.

Most aggressive lymphomas are sensitive to first-line immunochemotherapy and are in first Complete Remission (CR) with initial therapy. CR significantly decreases the risk of recurrence and increases survival. However, a cure is not guaranteed and approximately one third of lymphoma patients have a relapse disease.

FDG PET/CT is a valuable noninvasive tool in the evaluation of lymphomas, especially to differentiate viable lymphoma and fibrosis or necrosis in residual mass.

The majority of relapses are diagnosed based on clinical symptoms reported by patients. And the role of FDG PET/CT for routine surveillance of patients after treatment is controversial.

However, many medical centers use routine follow-up FDG PET/CT in addition to physical examination and laboratory analysis to detect subclinical relapse.

Thus, we can imagine a good timing to routine FDG PET/CT when the tumor burden is small in the asymptomatic window.

Survival improvement for relapse detected by routine follow-up imaging is not clearly established compared to diagnosis by clinical symptoms.

Several studies tried to assess the value of follow-up FDG PET/CT but population, type, timing and duration of surveillance imaging was very heterogeneous.

Inclusion Criteria:

• first diagnosis of aggressive lymphoma, complete metabolic remission after a first-line of chemotherapy, no relapse in the first year after the end of treatment

Exclusion Criteria:

• minor patient, pregnant woman, legal protection (legal curatorship / guardianship), absence of consent

All patients were examined every 3 to 4 months during the first two years, then every 6 months for three years, including physical examination and blood-test.

One group (group 1) of patients received a systematic routine surveillance FDG PET/CT at 12 months (PET/CT1y) according to hematologist team and the other group (group 2) did not receive routine follow-up FDG PET/CT at 12 months (non PET/CT1y).

None patient was symptomatic the first year. A median follow-up of 24 months at the end of treatment was required.