Retroperitoneal metastases in testicular cancer: Role of CT measurements of residual masses in decision making for resection after chemotherapy

PURPOSE: To determine the relative importance of computed tomographic (CT) measurements for the prediction of histologic findings in residual masses i n patients with nonseminomatous testicular cancer. MATERIALS AND METHODS: Measurements of the maximum transverse size of retro peritoneal metastases before and after chemotherapy were available in 641 p atient!,who underwent resection after chemotherapy while their levels of tu mor markers were normal. Radiologic measurements of mass size and clinical characteristics (histologic findings in primary tumor and levels of alpha-f etoprotein, human chorionic gonadotropin, and lactate dehydrogenase before chemotherapy) were related to histologic findings in the residual mass with logistic regression analysis. RESULTS: At resection, 302 patients had benign tissue, and 339 had residual tumor (mature teratomas or cancer). Tumor was more frequent in larger mass es after chemotherapy but was unrelated to mass size before chemotherapy. I nclusion of the reduction in size significantly improved the logistic regre ssion model, which included mass size after chemotherapy. This model was fu rther improved with the addition of clinical characteristics. Areas under t he receiver operating characteristic curves increased from 0.74 to 0.77 and 0.83 with these models. CONCLUSION: A small retroperitoneal mass after chemotherapy is an important predictor of benign histologic findings in residual masses in patients wit h nonseminomatous testicular cancer. However, better predictions can be mad e when the reduction in size and clinical characteristics are considered as well. Decisions regarding resection should be based on the combination of these characteristics rather than on only mass size after chemotherapy.