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Genetic Diagnosis Yields Benefit in GIST Therapy
At the 2021 ONS Congress, researchers discuss the importance of genetic diagnosis in gastrointestinal stromal tumor (GIST) therapy. Gastrointestinal stromal tumors (GIST) occur in 5-25% in the NF1 population, with higher rates found incidentally upon autopsy.
Researchers presented a case study involving a 43 year old male patient that had been experiencing nausea vomiting, and abdominal pain for one month. Of note, the patient has a family history of type 1 neurofibromatosis (NF1), a rare genetic disorder known for its variable expressivity of clinical features and risk for tumor formation, in his niece.
An abdominal CT scan revealed mild bowel obstruction with multiple hyper- enhancing nodules in the central pelvis with studding appearance along the small bowel, deemed as a possible malignancy. Upon partial small bowel resection, pathology disclosed multiple T1N0 gastrointestinal stromal tumors (GISTs) that were KIT and PDGFR gene mutation negative.
Upon physical examination, numerous cutaneous nodules on his trunk were noted as possible neurofibroma.
Prior to genetic evaluation, imatinib had been administered. The patient was referred for genetic counseling due to multiple family members consistent with autosomal dominant inheritance, although only his niece was formally evaluated. Genetic results discovered a pathogenic splice site mutation in the NF1 gene noted as c.7806+2T>C. In turn, Imatinib treatment was discontinued, and the patient is monitored through abdominal CT scans every 6 months, currently remaining stable.
To conclude, it has been confirmed that a genetic diagnosis aids in the determination of management approach compared to a sporadic GIST diagnosis. By confirming a genetic diagnosis informs the patient and provider(s) of the possibility for other malignancies, suggested surveillance, management for other NF1 comorbidities, and allows for cascade testing of at-risk relatives. -Alexis Hyams
