Gastrointestinal Stromal Tumors: Innovation from Diagnosis to Treatment Based on 15 Years of Experience of a Peripheral Hospital in Portugal

Abstract

Aim: To investigate fifteen years of experience, in managing GISTs, according to best clinical
practice, on a peripheral Portuguese Hospital. Define the behavior of GIST’s and the association
between the histological, immunehistochemistry characteristics and disease progression.
Question if the optimal treatment was delivered in GIST patients, based on medical evidence,
where limitations on evaluating molecular signatures exists.
Methods: A retrospective analysis of cases treated in Hospital of Entre Douro and Vouga from
1 January 1999 to 31 December 2014 was performed. Demographic characteristics were evaluated
related to tumor characteristics according to the National Institute of Health criteria and
disease progression. All patients were evaluated in a multidisciplinary team. An expert treatment
decision was made according to the National Institute of Health criteria of Gastrointestinal
stromal tumor’s risk of recurrence after surgery. Statistical study was performed using
SPSS version.
Results: Sixty-three cases were evaluated, 61.9% in female patients and 38.1% male. The median
age at diagnosis was 69 years. A progressive increase in the incidence of GISTs was documented
since 1999 to 2014. The most common source locations was the stomach with forty-five
patients (71.4%), When assessing the Mitotic count, 27% was superior to 5 mitosis/50HPF and
73% was inferior to 5 mitosis /50HPF.
Sixty-two patients underwent surgery with R0 resection rate of 94% Immunohistochemistry
was performed in all patients, and sixty-one patients were positive for CD117. Only two patients
were CD117 negative. No KIT gene mutation analysis was performed.
Regarding the biological risk of recurrence or metastasis, according to the National Institute of
Health, 25,4 % of the patients had a very high risk, 19,0% had an intermediate risk, 34,9% had
a low risk and 20,6 % had a very low risk.
Of the 63 patients, 25.4% (n=16) were submitted to adjuvant treatment with imatinib (400 mg/
daily) during 3 years. Only 7.9% (n=5) received palliative treatment with imatinib and sunitinib.
Only in 11% of the patients the disease progressed (median time to progression of 36 months).
The mortality rate was 12.7% (n=8). Fifty-five patients were alive (87.3%) at the end of this
retrospective study.
Conclusions: Mutation analysis was not performed, which might have influenced the treatment
and prognosis. Optimize therapy based on molecular signatures are extremely important for a
cost-effective treatment.