Major basic protein as a marker of malignant potential in trophoblastic neoplasia

OBJECTIVE: We tested whether serum pregnancy-associated major basic protein levels distinguish between benign and malignant trophoblastic disease. STUDY DESIGN: We compared serum pregnancy-associated major basic protein levels in seven patient groups: nonpregnant and pregnant controls, partial moles, complete moles, persistent moles, placental-site trophoblastic tumors, and choriocarcinoma. RESULTS: The results showed that patients with partial and complete moles had elevated serum pregnancy-associated major basic protein levels comparable to normal pregnancy. In contrast, patients with persistent mole, placental-site trophoblastic tumors and choriocarcinoma had low median serum levels comparable to those of the nonpregnant controls. Significant differences were shown between the complete and persistent mole groups (p = 0.0001) and between the complete mole group and the choriocarcinoma group (p = 0.0001); however, persistent moles were indistinguishable from choriocarcinoma (p = 0.2010). CONCLUSION: Serum pregnancy-associated major basic protein levels thus distinguish between benign disorders, such as pregnancy and partial and complete moles, and trophoblastic tumors, such as persistent moles and choriocarcinoma: The absence of elevated serum levels of pregnancy-associated major basic protein may be useful clinically to indicate a more aggressive or frankly malignant tumor.