GI Stromal Tumors Clinical Practice Guidelines (2018)

The clinical practice guidelines on GI stromal tumors were released on May 28, 2018, by the European Society for Medical Oncology and the European Network for Rare Adult Solid Cancer.^[1]

Diagnosis and Pathology/Molecular Biology

Endoscopic ultrasound assessment and then follow-up is the standard approach for patients with esophagogastric or duodenal nodules <2 cm.

Biopsy/excision is the standard approach to tumors ≥2 cm in size.

Mutational analysis inclusion in the diagnostic work-up of all GISTs should be considered standard practice (with the possible exclusion of <2 cm non-rectal GISTs).

Management of Local/Locoregional Disease

The standard treatment of localized GISTs is complete surgical excision of the lesion, with no dissection of clinically negative lymph nodes.

If laparoscopic excision is planned, the technique needs to follow the principles of oncologic surgery.

When R0 surgery implies major functional sequelae and preoperative medical treatment is not effective, the decision can be made with the patient to accept possible R1 resection.

Adjuvant therapy with imatinib for 3 years is the standard treatment of patients with a significant risk of relapse.

PDGFRA D842V-mutated GISTs should not be treated with adjuvant imatinib.

Adjuvant treatment should be avoided in NF1-related and succinate dehydrogenase (SDH) expression-negative GISTs.

Patients at a very high risk of peritoneal relapse (in case of tumor rupture at the time of surgery) should be considered for imatinib therapy.

If R0 surgery with no expected major sequelae is not feasible, pre-treatment with imatinib is standard.

Management of Advanced/Metastatic Disease

Imatinib is the standard treatment of locally advanced inoperable and metastatic disease.

Imatinib is also the standard treatment for patients with metastatic disease who have had all lesions removed surgically, although surgery is not recommended as a primary approach in the metastatic setting. The standard dose of imatinib is 400 mg daily.

Standard treatment of patients with KIT exon 9 mutation is 800 mg daily of imatinib.

In the metastatic setting, treatment with imatinib should be continued indefinitely, unless intolerance or specific patient request to interrupt.

Surgery of residual metastatic disease should be individualized after making the decision with the patient in the case of uncertainty.

Surgical excision of progressing disease should be considered for an individual patient with limited progression, while continuing imatinib.

In the case of tumor progression on 400 mg of imatinib, the dose can be increased to 800 mg daily (with the exception of insensitive mutations).

In the case of confirmed progression or rare intolerance on imatinib, standard second-line treatment is sunitinib.

Regorafenib, at the dose of 160 mg daily for three out of every four weeks, is the standard third-line therapy for patients progressing on or failing to respond to imatinib and sunitinib.

Rechallenge or continuation of treatment beyond progression with imatinib to which the patient has already been exposed is an option.

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