Ga-67 uptake: A predictor of post-therapy active residual disease and clinical outcome in patients with diffuse large cell lymphoma

Abstract

Purpose: Diagnosis and treatment of post-therapy active residual disease (PTARD) is essential in patients with lymphoma. After treatment, Ga-67 scan is considered as a useful technique for monitoring response in these patients. Material and Methods: Between December 1998 and January 2004, 63 patients histopathologically diagnosed with Diffuse Large Cell Lymphoma (DLCL) were studied. Patients were evaluated before and after treatment with a whole body Ga-67 scan in addition to other imaging techniques. International Prognostic Index (IPI), and clinical variables were determined according to criteria reported by the International non-Hodgkin's Lymphoma Prognostic factors Project. Results: Among the patients with positive computed tomography (CT) scan, the 5-year relapse-free and overall survival rates were 70% and 78% for those with negative scans compared with 23% and 35% for gallium-positive patients, respectively (p< 0.004, p<0.008). Furthermore, the 5-year relapse-free and overall survival rates were 92% and %91 for those with negative scans compared with 33% and 40% for gallium-positive patients (p< 0.001, p< 0.004), among the patients with negative CT scan. All patients were divided into two groups according to the IPI index after therapy and the 5-year relapse-free survival rate for negative Ga-67 scan is 75%, as compared with 42% for restaging positive Ga-67 scan (p<0.004) in the patients with low IPI score. Conclusion: Ga-67 scan is capable of detecting PTARD that remains undetected at CT and it appears to be a better predictor of outcome than previously evaluated pretreatment risk factors in patients with DLCL.