Mitotic activity and the Ki67 proliferation index are the most important parameters related to the recurrence of gastrointestinal stromal tumors (GISTs), according to a new study published in the Turkish Journal of Gastroenterology.

According to the authors, although platelet-derived growth factor receptor-β (PDGFRβ) may be used to diagnose GIST, in the case of cKIT negativity, it is not an indicator of tumor recurrence as in other non-GIST tumors.

PDGFRβ is associated with poor prognosis in a number of mesenchymal and epithelial tumors. However, its association with GIST is not well documented.

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Here, a team of researchers led by Figen Barut, MD, professor of medical pathology at Zonguldak Bulent Ecevit University, Turkey, explored the relationship between patients’ clinicopathological criteria and the recurrence of GIST and evaluated the role of PDGFRβ expression in recurrence and clinicopathological findings.

They did so by retrospectively analyzing 40 patients with GIST. They found that tumor recurrence was associated with male gender, serosal localization, surgical margins positivity, risk group, mitotic activity, and Ki67 proliferation index. However, it was not associated with the expression of PDGFRβ.

The authors also suggested that a cutoff value of 13%, instead of the commonly accepted 10%, of the Ki67 proliferation index would be more specific and sensitive.

“Despite . . . the limited number of cases, we strongly believe that our study will provide an important contribution to the studies in this field,” the researchers wrote.

Most cases of GIST are caused by a gain of function mutation in the cKIT proto-oncogene. The KIT gene encodes transmembrane tyrosine kinase proteins, which become constitutively active due to the mutation favoring cell growth and division over apoptosis, leading to the formation of tumors.

In 5 to 10% of GIST cases, there is a mutation in the PDGFRA gene, which codes for a protein that belongs to the same family as KIT. Mutations also cause PDGFRA to be constitutively active, leading to tumor formation in a similar way.


Kaymaz E, Taşdöven İ, Barut F. The relationship of clinicopathological findings and PDGFR-β expression with tumor recurrence in gastrointestinal stromal tumors. Turk J Gastroenterol. 2021;32(12):1038-1048. doi:10.5152/tjg.2021.21148