OBJECTIVETo study the expression of the small subunit ribonucleotide reductase (R2) in gestational trophoblastic diseases (GTD) and to assess its prognostic value.

METHODSThe expression of R2 was detected with immunohistochemical method in 15 cases of normal villi, 38 cases of hydatidiform mole (HM), 42 cases of invasive moles (IM) and 18 cases of choriocarcinoma (CC).

RESULTSR2 expression in HM, IM and CC was significantly increased compared with that of normal villi (P=0.000). There were no significant differences in R2 protein expression among HM, IM and CC. Among 38 cases of HM, R2 expression in 8 cases with malignant transformation was significantly higher than in 30 cases of non-malignant transformation mole (P=0.02). Preoperative chemotherapy of gestational trophoblastic tumor including IM and CC did not influence the R2 expression. Compared with patients of stage I (WHO), the R2 protein in gestational trophoblastic tumor (GTT) patients of stage III or stage II was significantly increased (P=0.023 and P=0.038, respectively). The value of R2 in GTT patients with middle or high risk in WHO prognostic scoring system was higher than in the patients with low risk (P=0.018 and P=0.006, respectively).

CONCLUSIONR2 expression in GTD is increased, which may be associated with the hyperplasia of trophoblasts, malignant transformation of hydatidiform mole and drug resistance of trophoblastic tumor.