Gallium scans in the evaluation of residual masses after chemotherapy for seminoma.

Abstract

PURPOSE To assess the ability of gallium scans to determine whether residual masses consist of viable tumor or necrotic fibrous tissue after chemotherapy for seminoma. PATIENTS AND METHODS Thirty-two patients were enrolled and 27 were assessable. Patients receiving first-line or salvage chemotherapy had gallium scans performed during their first and last scheduled course of chemotherapy and results were compared with restaging computed tomographic (CT) scans and subsequent clinical outcome. RESULTS Of 27 assessable patients, 22 received first-line chemotherapy (group A) and five salvage chemotherapy (group B). Eight patients were not gallium-avid before chemotherapy despite obvious clinical and radiographic evidence of metastatic seminoma. Eighteen of 19 gallium-positive patients had a persistent mass postchemotherapy on abdominal CT. Of 16 patients in group A whose tumors were gallium-avid, all 16 had normalized gallium scans after chemotherapy. However, two of these 16 patients recurred in their original disease site. In group B, there were three patients with gallium-avid tumors and all three had normalized scans postchemotherapy. Two patients who were not gallium-avid (one each in group A and B) also developed recurrent disease. Twenty-four of 27 patients are alive with no evidence of active disease at a median follow-up time of 18 months, including 20 with more than 1 year of follow-up data. CONCLUSION Eight of 27 patients had false-negative gallium scans at the time of diagnosis. All nineteen gallium scans that were initially positive reverted to normal after chemotherapy. Two of 19 patients' follow-up gallium scans were false-negative. We therefore feel that gallium scans have minimal value in the prechemotherapy or postchemotherapy evaluation of metastatic seminoma.