Researchers from Norway uncovered cytogenetic differences between gastric and nongastric gastrointestinal stromal tumors (GISTs) in their analysis of more than 300 GIST samples.

“Based on the examination of such a large dataset, we were able to elucidate the roles of individual chromosomes in the pathogenesis of tumors with different genotypes and sites of origin, and provide further evidence that gastric and non-gastric GISTs develop via different cytogenetic pathways,” the researchers said.

Gorunova et al identified clonal chromosome aberrations in 81% of GIST samples analyzed (n=306). Most (89%) karyotypically abnormal samples were near-diploid. More than half (149/226) GISTs were constituted by one clone only, while the remaining demonstrated clonal evolution. A small proportion of cases (21/226) showed unrelated clones.


Continue Reading

Karyotypically complex tumors (ie, with >5 chromosomal changes, n=91) were more often nongastric, larger, and more mitotically active, and had a higher risk of tumor rupture and recurrence than those displaying simple karyotypes (ie, with ≤5 chromosomal changes, n=135).

Read more about GIST etiology

The comparison of the cytogenetic profiles of gastric and nongastric GISTs revealed differences in chromosome losses. The loss of 14q was more frequently observed in gastric GISTs (79% vs 63%), while the losses of 1p (23% vs 88%), 15q (18% vs 77%), and 22q (38% vs 67%) were more common in nongastric GISTs. Nongastric GISTs also had higher rates of 2p (30% vs 3%) and 13q (30% vs 11%) losses.

Further analysis showed that the main differences in the cytogenetic profile between gastric and nongastric GISTs emerge early in karyotypic evolution.

In addition, the researchers found that gastric PDGFRA-mutated GISTs had a lower incidence of 22q losses (18% vs 43%), but a higher incidence of 1p losses (42% vs 22%) than gastric KIT-mutated GISTs.

“A better understanding of the variable cytogenetic pathways during tumor progression may help to improve diagnostic, prognostic, and treatment decisions,” the researchers concluded.

Reference

Gorunova L, Boye K, Panagopoulos I, et al. Cytogenetic and molecular analyses of 291 gastrointestinal stromal tumors: site-specific cytogenetic evolution as evidence of pathogenetic heterogeneity. Oncotarget. 2022;13(1):508-517. doi:10.18632/oncotarget.28209