Result of FDG PET Imaging After Chemotherapy +/− Immunotherapy Is a Significant and Independent Prognostic Indicator of Outcome for Patients with Follicular Lymphoma: Survey From a Single Institution

FDG positron emission tomography (PET) is the mainstay of response evaluation in some lymphoma subgroups such as DLBCL or HL according to Cheson criteria 2007. Due to its indolent behaviour, PET restaging has been poorly explored in Follicular Lymphoma (FL)

The analysis was retrospectively conducted in pts with FL who underwent whole-body 18F-FDG-PET as part of response evaluation at the end of first line or savage treatment program at our institution from August 2001 to June 2010.

Seventy five patients were identified. Main clinical characteristics: median age 58 (range 26– 78); male 37 pts; B symptoms 6 pts; bulky disease 5 pts; stage IV 42 pts; bone marrow involvement 32 pts. Fifty-five pts were evaluated after first line treatment program, while 20 pts after salvage therapy program. Main chemotherapy regimen: CHOP or CHOP-like 38, CVP 11, polichemotherapy containing high-dose cytosine-arabinoside 11, fludarabine containing regimens 4. Furthermore, 19 pts underwent autologous peripheral stem-cell transplantation after either first line or salvage therapy. Eleven pts also received consolidation radiotherapy. Forty-two pts received Rituximab during chemotherapy. At the end of treatment, 54 pts reached complete remission as confirmed by PET. With a median follow-up of 53 months, a significantly lower actuarial 4yr PFS was observed in post-treatment PET+ versus. PET- patients: 35.1% vs. 74.8% (log rank p<0.01). Among all other prognostic factors analyzed (B-symptoms, bulky disease, chemotherapy regimens, chemotherapy vs chemoimmunotherapy, first line therapy vs salvage chemotherapy), only stage IV showed a correlation with PFS.

In a multivariate Cox model including all patients, post-treatment PET+ (HR 2.20; C.I. 95%: 1.02–4.76 p<0.04) and Stage IV (HR 3.08; C.I. 95%: 1.23–7.73 p<0.01) were unfavorable predictors for PFS.

This retrospective study demonstrates that post-treatment negative PET is a powerful predictor for PFS. Patients who are PET- can expect a prolonged PFS either in first line or successive lines of treatment. Future clinical trials are needed to evaluate a PET oriented approach focused on improving outcomes according to PET response.

No relevant conflicts of interest to declare.