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Open Access Research article

Prevalence of gastrointestinal stromal tumour (GIST) in the United Kingdom at different therapeutic lines: an epidemiologic model

Justyna M Starczewska Amelio1, Javier Cid Ruzafa1*, Kamal Desai1, Spiros Tzivelekis2, Dominic Muston3, Javaria Mona Khalid1, Philip Ashman3 and Andrew Maguire1

Author Affiliations

1 Health Economics and Epidemiology, Evidera, Metro Building, 6th floor, No.1 Butterwick, London W6 8DL, UK

2 Global Market Access, Bayer Pharma AG, Berlin S157, 03, 305, Germany

3 Health Economics, Bayer plc, Strawberry Hill, Newbury RG14 1JA, UK

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BMC Cancer 2014, 14:364  doi:10.1186/1471-2407-14-364

Published: 24 May 2014

Abstract

Background

The prevalence of patients with gastrointestinal stromal tumourgst (GIST) who fail currently available treatments imatinib and sunitinib (third-line treatment-eligible GIST) is unknown, but is expected to be below an ultra-orphan disease threshold of 2/100,000 population used in England and Wales. Our study was designed to estimate the prevalence and absolute number of UK patients with unresectable/metastatic GIST at first-, second- and eventually third-line treatment.

Methods

Our open population model estimates the probability that the prevalence of UK third-line treatment-eligible GIST patients will remain under the ultra-orphan disease threshold. Model parameters for incidence, proportion of unresectable/metastatic disease and survival estimates for GIST patients were obtained from a targeted literature review and a UK cancer register. The robustness of the results was checked through differing scenarios taking extreme values of the input parameters.

Results

The base-case scenario estimated a prevalence of third-line treatment-eligible GIST of 1/100,000 and a prevalence count of 598 with a 99.9% likelihood of being below the ultra-orphan disease threshold. The extreme scenarios, one-way and probabilistic sensitivity analyses and threshold analysis confirmed the robustness of these results.

Conclusions

The prevalence of third-line treatment-eligible GIST is very low and highly likely below the ultra-orphan disease threshold.

Keywords:
Epidemiology; Prevalence; Gastrointestinal stromal tumour; GIST; Model; Ultra-orphan disease