DNA content as a prognostic index in gestational trophoblastic neoplasia

Abstract

Hydatidiform mole will progress to malignant gestational trophoblastic neoplasia (GTN) in some cases. Aneuploidy and high proliferative activity are associated with malignant tumors. Molar pregnancy tissue was considered a precursor to malignant GTN, and was studied retrospectively using paraffin-embedded tissue to determine whether aneuploidy or proliferative rates measured on molar tissue could predict a malignant course. Tissues from 51 complete hydatidiform moles were analyzed for nuclear DNA content by flow cytometric techniques. A chart review identified the clinical course after evacuation of the mole. A satisfactory DNA histogram was generated in 40 cases. Of the 40 patients, 22 (55%) had spontaneous resolution, and 18 patients (45%) required treatment for persistent GTN. The molar tissue was found to be euploid in 27 cases and aneuploid in 13 cases. Eight of the twenty-seven euploid cases (30%) required treatment after evacuation, whereas 10 of the 13 aneuploid cases (77%) required treatment after molar evacuation. Proliferative index (PI) was compared with treatment requirements. Average PI was 0.11 ±0.10 for the treatment group and 0.08 ± 0.06 for the spontaneous resolution group. The correlation of clinical course with ploidy was significant ( P < 0.01). The association with proliferative index was not ( P > 0.05). Aneuploidy, therefore, identifies a high-risk group of molar pregnancies, and may represent those that have undergone one stage of malignant transformation.