A new case series has revealed a possible association between gastrointestinal stromal tumor (GIST) and peritoneal mesothelioma (PM). The series, published in the Annals of Surgical Oncology, found that 1 in 17 patients with GIST who were undergoing resection also had PM.

“Although GISTs are seen in isolation in a majority of cases, several single-institution studies have shown that 14%–33% of GISTs occur in patients with other malignancies,” the authors wrote. “However, GIST co-occurrence with peritoneal mesothelioma, a mesothelioma subtype found only in the abdominal cavity, remains poorly understood.”

The research team conducted a retrospective chart review on 137 patients with GIST at a single center in San Diego, California, between July 2010 and June 2021. Of all patients undergoing GIST resection during this period, 8 were found to also have PM, or 1 in 17 patients, which is a much higher percentage than that expected if the 2 conditions were independent.

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Furthermore, in 7 of the 8 cases, the cancers were colocalized. In all cases, GIST was diagnosed first and the PM was identified during the diagnosis or resection. The authors note that the potential association could have ramifications for adjuvant therapy.

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Following the resection, tumor samples were obtained to determine possible oncogenic mutations that could guide subsequent treatment, given that it is possible that multiple primary tumors can occur in patients with an underlying hereditary cancer predisposition. Four of the 8 patients with both GIST and PM had a history of multiple tumors, but no common pathogenic germline mutations were found in this series.

Based on the differences between the presentation in the patients with both GIST and PM and those with each disease in isolation, the authors conclude the tumors have a nonindependent relationship that is possibly associated with tumor symbiosis or as-yet undetermined genomic drivers. Further studies will be required to elucidate more details about this relationship.


Courelli AS, Sharma AK, Madlensky L, et al. Co-localization of gastrointestinal stromal tumors (gist) and peritoneal mesothelioma: a case series. Ann Surg Oncol. Published online July 18, 2022. doi.10.1245/s10434-022-12211-x