Elsevier

European Journal of Cancer

Volume 41, Issue 18, December 2005, Pages 2868-2872
European Journal of Cancer

Incidence of gastrointestinal stromal tumours is underestimated: Results of a nation-wide study

https://doi.org/10.1016/j.ejca.2005.09.009Get rights and content

Abstract

Gastrointestinal stromal tumours (GIST) are identified by their specific morphology added with immunohistochemical staining with anti-CD117, the phenotypic marker for GIST in the majority of cases. In this study the reported incidence of GIST and GIST-like tumours before and after the routine availability of the specific diagnostic marker CD117 antigen was investigated. All patients with GIST or GIST-like tumours were selected from PALGA, a nation-wide network and registry of histo- and cytopathology in the Netherlands, to calculate the incidence in 1995 and longitudinally over time between 1998 and 2003. Pathological reports were retrieved to assess the type of immunostaining used and to assess the risk category for malignant behaviour according to the recently published consensus criteria. The annual incidence of GIST as distilled from the national pathology registry increased from 2.1 per million inhabitants in 1995 to 12.7 per million inhabitants in 2003. The incidence of GIST-like tumours decreased from 17.6 per million inhabitants in 1995 to 12.7 per million inhabitants in 2003. The incidences were stable from 2000 onwards. Additional analysis in 2003 indicated that more than 90% of the GIST tested was CD117 positive, compared to only 4% of the GIST-like tumours. Almost 50% of the GIST was considered to be at high-risk for malignant behaviour, according to the consensus criteria. The increased incidence of GIST 1995–2003 is related to increased understanding of GIST pathobiology and the routine availability of the diagnostic immunohistochemical antibody directed against the CD117 antigen.

Introduction

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumours of the gastrointestinal tract 1, 2. These tumours can be lethal; five-year survival ranges between 35% and 65% and depends on tumour size, mitotic index and location.[3] The identification of GIST has become important since specific, pathogenesis-targeted treatment with Kit tyrosine kinase inhibitor, imatinib mesylate (Glivec®) has become available, which has demonstrated promising clinical results 4, 5, 6. Before the introduction of imatinib, patients with inoperable GIST had limited therapeutic options, with a low response rate (less than 10%) to conventional chemotherapy 4, 7.

Information on the true incidence and prevalence of GIST is however, scarce, due to previous lack of well-defined pathologic criteria. Recent insights into the origin and pathogenesis of GIST revealed that pathologic activation of Kit signal transduction is a central event of GIST pathogenesis, which usually leads to expression of Kit protein (CD117) 1, 2. This resulted in the development of a reliable phenotypic marker for GIST (CD117 antigen) and a major reappraisal of the classification of GIST and GIST-like tumours over the past 3–4 years 4, 8. Recent data from Sweden however may indicate that, on basis of CD117 testing, the annual incidence of GIST, has been largely underestimated [9].

The aim of the present study was to investigate the reported incidence of GIST and GIST-like tumours before and after the availability of the specific diagnostic marker CD117 antigen in a nation-wide study, making use of the unique situation of a national pathology registry covering 100% of pathology labs in the country. In addition, the metastatic risk index of reported GIST was assessed.

Section snippets

The PALGA registry

Data for this study were obtained from PALGA, a nation-wide network and registry of histo- and cytopathology, which contains standardised abstracts of all 16 million inhabitants of The Netherlands since 1990. The abstracts contain amongst others encrypted patient identification, demographic data and a summary of the pathology report coded in accord with SNOMED terminology. The registry is both used for daily patient-care as for national and international scientific research.

Retrieval of patients with GIST and GIST-like tumours

From the PALGA

Incidence of GIST and GIST-like tumours

The total annual incidence of GIST or GIST-like tumours increased from 20.8 per million inhabitants in 1995 to 25.4 per million inhabitants in 2003 (Table 1 and Fig. 1). Simultaneously, the annual incidence of GIST increased from 2.1 to 12.7 per million inhabitants whereas the annual incidence of GIST-like tumours, mostly leiomyomas and leiomyosarcomas, decreased from 18.7 to 12.7 per million inhabitants.

Data from the abstracts of the pathology reports showed that in 1995 about 72% of GIST was

Discussion

The present study shows that the reported annual incidence of GIST increased from 2.1 per million inhabitants in 1995 to 12.7 per million inhabitants in 2003 (206 patients). As a result, the incidence of GIST-like tumours decreased from 18.7 per million inhabitants in 1995 to 12.7 per million inhabitants in 2003. Our results also showed that almost 45% of GIST were considered to be at high-risk for malignant behaviour in 2003.

The increased incidence of GIST may be explained by an improved

Conflict of interest statement

None declared.

Acknowledgements

The contribution to this study of the Dutch national pathology database ‘Stichting PALGA’ and the additional support of the individual pathological laboratories are fully acknowledged. Prof Hogendoorn acts in the (inter)national advisory board of Novartis-Pharma; this study was supported by an unrestrictional research grant of Novartis-Pharma, Arnhem, The Netherlands.

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