Increase in the incidence of gestational trophoblastic disease in The Netherlands

The objective of this study is to determine the incidence and time trends of gestational trophoblastic disease (GTD) in The Netherlands using population-based data.

Data on patients with a pathologically confirmed diagnosis of GTD from 1995 to 2008 were obtained from PALGA, a national archive containing all histopathology reports in The Netherlands. Data on number of deliveries were obtained from the Database of Statistics Netherlands.

During the study period, 4249 GTD patients were registered. Overall incidence rates of hydatidiform mole (HM), choriocarcinoma and placental site trophoblastic tumor (PSTT) were 1.34 per 1000 deliveries, 3.1 per 100,000 deliveries, and 1.0 per 100,000 deliveries, respectively. Incidence rates of HM increased from 1.02 per 1000 deliveries in 1995 to 1.56 per 1000 in 2001, an increase of 0.091 per year (95% CI 0.081-0.101). After 2001 incidence rates remained constant (increase per year -0.010, 95% CI -0.045-0.024). Maternal age and ethnicity are known to influence the risk of HM. Highest incidences were observed in women under 20 and over 40years of age. The proportion of deliveries accounted for by women over 40years of age increased from 1.5% to 2.9%, whereas women under 20 accounted for 1.5% of deliveries. The proportion of live births of Asian descent increased from 2.6% to 3.7%.

The incidence of GTD in The Netherlands increased significantly from 1995 to 2008. This can partially be explained by increased maternal age and increased proportion of live births of Asian descent. Part of the increase might result from improved diagnostic techniques. However, these factors do not seem to account for the total observed increase and part of the increase therefore remains unexplained.