Source: Gallium Scans in the Management of Patients With Hodgkin's Disease: A Study of 101 Patients
Emile Salloum, Debra Schwab Brandt, Vicente J. Caride, Eugene Cornelius, Daniel Zelterman, Warren Schubert, Thomas Mannino, Dennis L. Cooper
Journal of Clinical Oncology, Vol 15, No 2 (February), 1997 pp 518-527
Hodgkin's disease, like other medical conditions requiring intensive therapy, is dependent on clinical assessment and diagnostic imaging for careful follow-up. Computed tomography (CT) scans, which rely on anatomic evaluation, are invaluable for determining the extent of disease involvement at diagnosis. Gallium (67Ga) imaging utilizes the uptake of a radiometal (gallium) which has a high affinity for tumor cells and white blood cells. It is often used to assess and follow patients with Hodgkin's disease and Non-Hodgkin's lymphomas, as well as for monitoring various inflammatory processes. The literature has been unclear regarding the significance of negative post treatment scans.
The article cited above was designed to evaluate the predictive value and usefulness of periodic gallium scans in the management of patients with Hodgkin's disease. 101 patients treated for Hodgkin's disease between 1990 and 1994 had a positive 67Ga at the time of diagnosis. 67 patients had stage I or II disease and 34 with III to IV disease. Treatment included radiation therapy in 28 patients, chemotherapy in 27, and combined modality therapy in 46. All patients underwent 67Ga scans at the time of diagnosis, near the completion of treatment, and at follow-up evaluations.
The authors found that the 67Ga scans remained positive in four patients and were interpreted as negative in 97 patients, following treatment. Two of the four patients with positive scans died of progressive disease and the other two died. Of the 97 patients with negative scans, 16 relapsed, including 7.5% of those with stage I to II disease and 34.45 with stage III to IV disease. The negative predictive value of the 67Ga scans after therapy for all patients was 83.5%, however, a dichotomy was seen when calculated according to stage. Specifically, it was 92.4% for patients with stage I to II disease and 64.5% for those with stage III to IV disease (p < 0.01).
The conclusion put forth by the authors was that most patients with Hodgkin's disease have a negative gallium scan after treatment, and that a positive gallium scan should be considered a manifestation of gross residual disease. The predictive value for patients with advanced disease (stage III and IV) was significantly lower than for those with earlier stage (I and II) disease, with 1/3 of the latter group ultimately failing.
It is important to realize that gallium scans do not necessarily provide the final word in imaging studies and other modalities, including PET imaging may have impact on predictive value.