Thy-1 as a potential novel diagnostic marker for gastrointestinal stromal tumors.

PURPOSE

Only few immunohistochemical markers besides c-kit exist for gastrointestinal stromal tumors (GISTs). Thy-1, a cell-surface glycoprotein, is a marker for several types of stem cells and particularly for neuronal precursor cells. The aim of this study was to determine Thy-1 expression in GISTs.

MATERIALS AND METHODS

Fifty-seven surgically resected and paraffin-embedded GIST samples were analyzed by immunohistochemistry with peroxidase method for Thy-1 molecule.

RESULTS

Thy-1 was detected in the majority of 57 GIST samples (54 out of 57 patients, 95%). All samples were c-kit positive and 90% were CD34 positive. All three Thy-1 negative samples were CD34 positive, had a low proliferative index (Ki-67 <or= 10%) and were located in the upper gastrointestinal tract (one in esophagus and two in the stomach). As a tendency, Thy-1 negative patients had a better prognosis, although not reaching level of significance due to low numbers.

CONCLUSIONS

Thy-1 is expressed in the majority of GISTs, suggesting a novel, additional standard marker for identifying GIST. Future studies should focus on the role of Thy-1 in the pathogenesis of GIST and subsequently on its potential to act as a molecular target for adjuvant therapy with new molecular antitumor agents.