Centralised registration of gestational trophoblastic disease and trends in incidence

To the Editor,

We read with interest the paper by Salehi et al. [1] in a recent issue of Acta Oncologica. In this study which included 3844 unique cases of hydatidiform mole (HM) from the combined records of two different registration systems, an incidence of 1.2 per 1000 deliveries was found. This conclusion supports our observations of an overall incidence rate of HM of 1.34 per 1000 deliveries [2]. In addition, the authors found that the incidence of HM increased during the period under study. Similarly, in our study an increasing trend in the incidence of HM was found in the Netherlands. This is in contrast to recent Asian studies, which show a declining trend in the incidence of HM [3]. Salehi et al. correctly stated that the higher incidence rates observed in some regions of Asia compared to rates found in Europe might be due to differences in regional reporting routines. The observed decrease in Asian incidence rates may be due to improved registration and more studies that use population-based data instead of hospital-based data. With this letter, we want to emphasise the importance of central registration of gestational trophoblastic disease (GTD) patients.

In the Netherlands, HMs are nationally registered at the Dutch Central Registry for Hydatidiform Mole (DCRHM) residing at the Radboud University Nijmegen Medical Centre (RUNMC). This voluntary registry serves as an epidemiological database and provides a national hCG assay service to gynaecologists. Since the first registration in 1977 until 2011, 4129 cases of GTD were registered. Additionally, in the Netherlands a unique nationwide network and archive was established in 1971 under the name of PALGA (Pathologisch Anatomisch Landelijk Geautomatiseerd Archief), in order to facilitate the optimal use of histopathology and cytopathology data for research and quality control [4]. Since 1991, this registration has encompassed all 64 pathology laboratories in the Netherlands and has complete coverage of all histopathological and cytopathological diagnoses made in the Netherlands. These registration systems enable research in order to improve the quality of care for GTD patients.

Unfortunately, with the exception of a few countries [5,6], most other European countries lack a registration system for GTD. Therefore, in 2009 the European Organisation for Trophoblastic Tissue Disease (EOTTD) was set up in order to improve registration and management of GTD in Europe [7]. In May 2010 the first meeting of the EOTTD was held in Lyon where an inventory of the current organisation of the epidemiology and management of GTD in different European countries was made. One of the goals of this European working group is registration of GTD cases in every country. Centralised registration will provide more insight on trends in the incidence of GTD and enable population-based studies with unbiased and non-selected data as was performed in the study by Salehi et al.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.