Nicked human chorionic gonadotropin in trophoblastic disease.

The objectives of this study were to determine: 1) whether high proportions of nicked human chorionic gonadotropin (hCG) in serum at the time of mole evacuation and during postmolar surveillance is indicative of trophoblastic malignancy and 2) to investigate whether measurement of nicked hCG provides clinically more useful information in the management of patients with trophoblastic disease than does measurement of total hCG alone. "Tumor marker" total hCG, intact hCG, and nicked hCG were measured in serial samples of serum from our serum bank of patients with representative types of trophoblastic disease. "Tumor marker" hCG has been shown to measure all aspects of the hCG molecule. At the time of presentation of all 45 patients, 83.5% of hCG was intact and 16.5% was nicked. These proportions became reversed as hCG declined either spontaneously after hydatidiform mole evacuation or with chemotherapy in patients with postmolar trophoblastic tumor or with metastatic trophoblastic disease. We conclude that the proportion of nicked hCG compared to intact hCG increases with trophoblastic disease resolution. Measurement of nicked hCG adds no useful clinical information to that provided by reliable measurement of total hCG.