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. (Am J Obstet Gynecol 1996;175:632-7.)