Comparison between 2-Deoxy-2-[18f]Fluoro-D-Glucose Positron Emission (FDG-PET) and Computed Tomography (CT) for Staging of Patients with Hodgkin’s Lymphoma (HL).

Hodgkin’s lymphoma (HL) is generally treated according to stage and risk profile. A tailored therapy decrease the risk of secondary malignancies which exceeds 10% in several historical series in patients with early stage disease. Anatomic imaging modalities, particularly computed tomography (CT), allow to good morphological imaging but lack sensitivity and specificity because the definition of lymph node involvement is based on size criteria. During the last decade FDG-PET has been introduced for noninvasive staging of lymphoma.

Herein we propose a prospective multicentric study with the aim to assess the impact of FDG-PET on the staging of pts with diagnosis of HL. A total of 135 consecutive pts coming from five Italian hematological Institutions underwent a FDG-PET scan in addition to conventional staging procedures, which include physical examination, laboratory data, bone marrow biopsy and imaging of the neck, thorax and abdomen using CT scan. All pts with disconcordant results were carefully evaluated with CT or NMR or ultrasound before starting, during and at the end of therapy. Pts characteristics: 70 male and 65 female, 106 (78.5%) with diagnosis of nodular sclerosis classical HL, 16 (12%) mixed cellularity classical HL, 8 (6%) lymphocyte-rich classical HL, 1 (0.5%) lymphocyte-depleted classical HL and 4 (3%) non specified HL. Standard staging procedures led to: 12 (9%) pts were stage I, 82 (61%) stage II, 26 (19%) stage III and 15 (11%) stage IV. FDG-PET and CT were concordant in 114 out 135 pts (84%). FDG-PET allowed to identify in 30 out 114 concordant stage more nodal (27 pts) or extranodal (3 pts: two spleen and one liver) involvement in comparison with CT imaging. In five out 114 concordant stage CT showed one more involved site in comparison with FDG-PET. FDG-PET results suggested an upstage in 17 pts (12,5%) and a downstage in 4 pts (3%). In these four pts FDG-PET did not confirm one nodal involvement and 3 extranodal involvement identified by CT (1 in the spleen, 1 in the liver and 1 in the lung). All these abnormal uptake sites were confirmed with other instrumental tests, we check after two or three cycles of chemotherapy and, after an accurate re-evaluation, they disappeared. Eleven pts (7%) with localized disease (I–II) at standard staging changed in an advanced stage as a result of the FDG-PET scan: four pts shifted from II to IV stage and seven pts from II to III stage. All pts with an upstaging PET were carefully analysed to confirm or not the PET positivity and in five out 17 of these pts the information provided by FDG-PET led to a change in the therapeutic options in particular for the extent of the radiation fields.

In conclusion our data confirm that conventional staging system has an high sensibility nevertheless in this large cohort of pts FDG-PET is a relevant noninvasive method that supplements conventional procedures and therefore should be used in combination with conventional diagnostics to stage HL particularly in pts with early stage, where a change in staging could modify disease management.