Gastrointestinal Stromal Tumors (GISTs) Follow-up

Updated: Sep 28, 2016
  • Author: Michael A Choti, MD, MBA, FACS; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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Follow-up

Further Outpatient Care

Follow-up care after curative operations is important because certain patients with recurrent disease may benefit from second surgical intervention and from systemic therapy with tyrosine kinase inhibitors for unresectable and/or metastatic disease. Follow-up includes physical examination and computed tomography (CT) scanning, and possibly periodical gastroscopies, as well.

For followup of gastric GISTs < 2 cm that have been completely resected, the National Comprehensive Cancer Network (NCCN) recommendations vary according to the presence or absence of high-risk features (eg, irregular border, cystic spaces, ulceration, echogenic foci, heterogeneity). For GISTs with high-risk features, the NCCN recommends considering abdominal/pelvic CT with contrast every 3-6 months for 3-5 years, then annually. For those without high-risk features, endoscopic surveillance at 6-12 month intervals may be considered. [36]

For followup of patients with metastic or persistent gross residual disease, the NCCN recommends followup with history and physical examination and abdominal/pelvic CT every 3-6 months. For patients with completely resected GISTs, the NCCN recommends history and physical examination every 3-6 months for 5 years, then annually, plus abdominal/pelvic CT every 3-6 months for 35 years, then annually. [36]

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Prognosis

GISTs manifest a wide variety of clinical behavior, from slow-growing indolent tumors to aggressive malignant cancers with the propensity to invade adjacent organs, metastasize to the liver, and recur locally within the abdomen. Clinical presentation provides the most overt evidence for distinguishing benign from malignant behavior. Histologic analysis of biopsy or operative specimens provides objective measures for diagnosis and helps predict clinical behavior.

The predominant prognostic factors in patients with GISTs include the size of the tumor, location of the tumor, and the mitotic rate. [74, 75, 76] To these may be added the ability or inability to achieve completely negative resection margins. The following characteristics appear to be the most predictive of aggressive behavior in GISTs:

  • Mitotic rate greater than 5 mitoses per 50 high-power fields (HPFs)
  • Size larger than 5 cm and 10 cm, which pose moderate and high malignant potential, respectively [16]
  • Location (small bowel GISTs of comparable size and mitotic rate are generally more aggressive than gastric GISTs)

Because no standardized staging system exists for stromal tumors of the GI tract and most series are small and heterogeneous, comparison of the different published survival rates is difficult. However, various reports of 5-year survival rates after R0 resection for GISTs range from 32-93%. In large series, this rate is about 50-60%.

The median survival after palliative resection is about 10 months, with a 5-year survival rate as high as 10%. These rates improve with the addition of imatinib. [68, 69, 74, 75] The disparity between patients presenting with localized primary disease (median survival of 5 y) and those presenting with metastasis or recurrent disease (median survival of 10-20 mo) is large.

Unfortunately, no absolute determinations can be made because even small lesions with low mitotic rates can metastasize or behave in a locally aggressive fashion. In 2002, Fletcher and colleagues proposed the following classification system to define the risk of aggressive or malignant behavior in GISTs [77] :

  • Very low risk: size < 2 cm and < 5 mitoses/50 HPFs
  • Low risk: 2-5 cm and < 5/50 HPFs
  • Intermediate risk: < 5 cm and 6-10/50 HPFs or 5-10 cm and < 5/50 HPFs
  • High risk: >5 cm and >5/50 HPFs or   >10 cm and any mitotic rate or any size and >10/50 HPFs

In 2009 Gold et al from Memorial Sloan-Kettering Cancer Center (MSKCC) developed a nomogram that uses tumor size, site, and mitotic index to predict relapse-free survival after resection of localized primary GIST. [78]

The NCCN criteria for risk stratification of primary GIST have not been incorporated into the AJCC staging but may be more helpful in determining individual risk for progressive disease, after margin-negative resection. [36] The stratification is by mitotic index (≤5 versus >5 per 50 HPF) and then further divided by tumor size (≤2 cm vs >2 cm; ≤5 cm vs >5 cm; ≤10 cm vs >10 cm) and tumor location (gastric, duodenum, jejunum-ileum, and rectum).

Gastric GISTs greater than 10 cm but less than or equal to 5/50 HPF mitotic index have only a 10% risk of progressive disease despite 34-57% risk of progressive disease in the other tumor locations. Gastric GISTs greater than 10 cm and a high mitotic index (>5/50 HPFs), however, have an equally high risk of progressive disease (86%) as GISTs in other locations.

Mutational status has both prognostic significance and impact on response to tyrosine kinase inhibitor therapy. In randomized clinical trials, the presence of a KIT exon 11 mutation was associated with better response, progression-free survival, and overall survival rates than KIT exon 9 mutant GISTs. The risk for progression and death were increased in patients with no detectable KIT or PDG-FRA mutations. [11]

Other factors found to have a negative impact on prognosis are as follows:

  • Tumor rupture during operation
  • Involvement of histologic margins
  • Lymph node involvement

In an analysis of 4,694 patients with localized GISTs from the National Cancer Data Base, Sineshaw and colleagues found that patients treated with adjuvant therapy had a 46% lower risk of death than patients treated with surgery alone, This survival benefit was significant for patients with GISTs larger than 10 cm. [79]

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Patient Education

Patients should be educated about as many aspects of the disease as possible, including diagnostic and therapeutic measures and options. GIST Support International has produced a patient education booklet entitled Understanding Your GIST Pathology Report.

Most importantly, patients should be apprised of the need for lifelong close clinical follow-up, even after complete resection of disease. Emphasize that GISTs have a propensity to recur.

For patient education resources, see the Cancer Center.

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