Cohort study of circulating tumor DNA posttreatment measurement and development of metastases in retinoblastoma

Tumor-specific circulating tumor DNA (ctDNA) is commonly detected in the blood of newly diagnosed children with retinoblastoma. A cohort study at Memorial Sloan Kettering Cancer Center (New York, NY) investigated the association of disappearance of ctDNA posttreatment with metastasis-free survival of retinoblastoma patients. In this cohort study of 24 patients, 96% of patients who had detectable ctDNA at diagnosis did not develop metastatic disease, and in each case, the plasma ctDNA completely disappeared after treatment (enucleation or intra-arterial chemotherapy). One patient who had persistent measurable ctDNA after treatment developed metastatic disease. The authors conclude that disappearance of plasma ctDNA after treatment for retinoblastoma may be associated with metastasis-free survival.