Trends in incidence for gestational trophoblastic disease over the last 20 years in a population-based study

Background: Gestational trophoblastic disease (GTD) represents a heterogeneous group of disorders. Wide variations in incidence rates are reported worldwide, probably explained by a lack of centralized databases and heterogeneity in case definition. The aim of the present study was to determine the trends in incidence of GTD in the last 20 years with the use of population-based data.

Patients and methods: Data on patients with pathologically confirmed diagnosis of GTD between 1994 and 2013 were obtained from PALGA, a nationwide archive containing all pathology reports in the Netherlands.

Results: In the 20-year period 6343 cases were registered with GTD, representing an overall incidence rate of 1.67 per 1000 deliveries per year. An initial rise in incidence rate was seen over the first 10 years (0.075 per year, 95% CI 0.040-0.109), followed by a stabilization from 2004 to 2013 (increase per year 0.011, 95% CI -0.017-0.040). Although partial hydatidiform mole (HM) was more common in earlier years, complete and partial HM reached comparable incidence rates of 0.68 and 0.64 per 1000 deliveries respectively from 2009 onwards. In the last decade, unspecified HM diagnosis declined significantly from 0.14 per 1000 deliveries in 2003 to 0.03 per 1000 deliveries (per year -0.011, CI -0.016-0.06), suggesting improved diagnostic analyses.

Conclusion: After an initial rise in GTD incidence in the Netherlands rates remained steady from 2004 onwards. As pathological confirmation is currently the norm and advanced pathological techniques are now widely available, true steady incidence rates may have been reached.