Background and objective: Therapy of both Hodgkin's disease (HD) and aggressive non-Hodgkin's lymphoma (NHL) with mediastinal presentation at the time of diagnosis is frequently followed by radiological detection of residual masses. Computed tomography (CT) scanning is generally unable to detect the differences between tumor tissue and fibrosis. Gallium-67-citrate single photon emission ((67)GaSPECT) can potentially differentiate residual active tumor tissue from fibrosis.
Design and methods: Seventy-five patients with HD or aggressive NHL presenting mediastinal involvement (64% with a bulky mass) were studied with CT and (67)GaSPECT at the end of combined modality therapy (chemo- and radiation therapy).
Results: After treatment, 3/3 (100%) patients with positive (67)GaSPECT and negative CT scan relapsed while only 1/18 (6%) patients with both negative (67)GaSPECT and CT scan did so. At the same time, 54 patients had a positive restaging CT scan (abnormal mass < 10% of size of initial mass). Of these patients, 13 had a positive (67)GaSPECT, 10 of whom (77%) relapsed; 41 had a negative (67)GaSPECT of whom 5 (12%) relapsed. The 4-year actuarial relapse-free survival rate was 90% for those with negative scans compared with 23% for gallium-positive patients (p < 0.000000).
Interpretation and conclusions: In lymphoma patients with mediastinal involvement, (67)GaSPECT should be considered, at least in patients who are CT positive, the imaging technique of choice for monitoring and differentiating the nature of any residual masses.