Endoscopy 2004; 36 - 27
DOI: 10.1055/s-2004-825009

Loss of Heterozygosity of Chromosome 9p and Loss of P16 INK4A Expression Are Associated with Malignant Gastrointestinal Stromal Tumours

M Sabah 1, R Cummins 1, M Leader 1, E Kay 1
  • 1Dept of Histopathology, Education & Research Centre, The Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9

Gastrointestinal stromal tumours (GISTs) are distinctive KIT positive mesenchymal neoplasms. The genetic alterations leading to the malignant behaviour of these tumours are not well characterized.

In this study, 21 cases of GISTs (8 low malignant potential, 9 primary malignant and 4 intra-abdominal recurrences) were examined by immunohistochemistry and evaluated for loss of heterozygosity (LOH) of the short arm of chromosome 9, using 6 microsatellite markers.

LOH with at least two markers at 9p region was a common finding in high risk GISTs (malignant and recurrent group) but absent in the low malignant potential group. Recurrent GISTs showed more frequent deletions than their primary tumours. All cases with LOH showed deletions at 9p21 region. Similarly, all malignant potential GISTs were immunoreactive for p16 whereas malignant GISTs were negative for p16.

These results suggest that p16 INK4A gene on 9p may contribute to the progression and/ or malignant transformation of GISTs