Gestational trophoblastic neoplasia after achieving a nondetectable serum human chorionic gonadotrophin level.

Objective To determine the risk of recurrent trophoblastic disease after normalisation of human chorionic gonadotrophin (hCG) levels in women with hydatidiform mole. Design A retrospective review of data from a national gestational trophoblastic disease centre. Setting The Trophoblastic Disease Unit, Dakar, Senegal. Sample Women with pregnancies affected by hydatidiform mole registered between 2006 and 2012. Methods The women were followed up in accordance with the hospital protocol ‘Score de Dakar’. For women who progressed to gestational trophoblastic neoplasia (GTN) the time to onset of GTN, treatment and evolution were evaluated. The rate of evolution to GTN after normalisation of hCG was determined. Main outcome measures Rate of occurrence of GTN after chemotherapy for hydatidiform mole. Results Five hundred and thirty-one women were diagnosed to have molar pregnancies. According to the hospital's protocol, 107 (20.2%) of these had chemotherapy and 224 (42.2%) had prophylactic chemotherapy. Five hundred and thirteen women (96.4%; 95% confidence interval [95% CI] 95.05–98.14%) achieved remission. Eighteen women (3.4%; 95% CI 1.86–4.94%) developed GTN (11 before remission and seven after remission). Seven women out of the 18 developed GTN after hCG normalisation (1.3%). Five of these seven were diagnosed beyond the recommended period of follow up. The mean interval to diagnosis of GTN was 18.7 months. These seven women underwent combination chemotherapy: five achieved complete remission whereas two died from GTN. Conclusions Cytotoxic therapy for hydatidiform mole does not prevent GTN, it delays its diagnosis and promotes GTN after normalisation of hCG.