Diagnostic Accuracy of Circulating Tumor DNA to Predict Retroperitoneal Histology in Patients Treated With Retroperitoneal Lymph Node Dissection for Testicular Germ Tumor.

Testicular germ cell tumor (GCT) has survival rates exceeding 90% and thus contemporary research has focused on reducing morbidity. While chemotherapy is efficacious, long-term effects are significant. Primary retroperitoneal lymphadenectomy (P-RPLND) has been offered, and postchemotherapy lymphadenectomy (PC-RPLND) is considered, based on residual node size, to reduce overtreatment. A significant number of patients have necrosis in the retroperitoneum and are thus overtreated. Circulating tumor DNA (ctDNA) may be used to determine which patients would benefit from RPLND. This retrospective analysis sought to determine the performance of ctDNA to detect retroperitoneal GCT only, teratoma only, and GCT/teratoma. All patients had a ctDNA obtained preoperatively and at 3, 6, and 12 months postoperatively. Ninety-two patients underwent P or PC-RPLND. The sensitivity, specificity, and positive predictive values (PPVs) and negative predictive values (NPVs) for detecting active GCT/teratoma in the entire cohort were 60%, 87%, 96%, and 30%, respectively. For GCT only these were 85%, 75%, 73%, and 86%. For teratoma only, these were 31%, 34%, 23%, and 43%. These findings indicate that patients with a positive ctDNA likely harbor active GCT and/or teratoma, as suggested by a PPV of 96%. Future studies may use whole-genome ctDNA assays to improve detection of teratoma and incorporate ctDNA into surveillance protocols.