Assessment of Her-2/neu expression in hydatidiform moles for prediction of subsequent gestational trophoblastic neoplasia

Objective.The aim of the present study was to asses the ability of Her-2/neu immunohistochemical staining of the molar tissue to predict the risk of developing gestational trophoblastic neoplasia (GTN).Methods.Sections prepared from 33 consecutive formalin-fixed paraffin-embedded archival reconfirmed hydatidiform mole tissue blocks were immunohistochemically stained for Her-2/neu. The staining was scored according to the subjectively evaluated intensity of staining and the proportion of stained villous cytotrophoblastic cells. Clinical data were abstracted from medical files.Results.23 patients had a complete and 10 a partial mole. Nine patients (27.3%) were diagnosed with GTN [7 of 23 patients with a complete mole (30.4%) and 2 of the 10 (20.0%) with a partial mole].A positive immunohistochemical Her-2/neu stain was found in 6 (18.2%) of the patients with hydatidiform mole (3 with a complete mole).The rate of Her-2/neu expression was somewhat higher in moles with subsequent GTN than in moles with an uneventful course (22.2% vs. 16.6%, respectively). The difference did not reach significance (Fisher's Exact Test, P = 0.55) possibly due to the small number of cases (power of < 5%).The sensitivity and specificity of Her-2/neu expression for prediction of GTN was 22.2% and 83.3%, respectively, and the positive and negative predictive value 33.3% and 74.1%, respectively.Conclusion.While the specificity of Her-2/neu immunohistochemical staining for prediction of GTN is relatively high, the low sensitivity and low positive and negative predictive value precludes its practical clinical use for prediction of post-molar GTN.The quest for a precise predictor of post-molar GTN should continue.