Population-based incidence and survival of gastrointestinal stromal tumours (GIST) in Girona, Spain.

BACKGROUND: Gastrointestinal stromal tumours (GIST) are rare malignancies characterised by their association with KIT oncogene mutations. Until now, population-based reports of the incidence or survival of kit-confirmed GIST have been rare, and none have originated in Southern Europe.
MATERIALS AND METHODS: We used the Girona Cancer Registry to identify malignant mesenchymal tumours of the digestive tract between 1994 and 2001, and performed c-kit testing in the tumour samples. Age-adjusted incidence rates and survival rates were calculated, and they were also analysed by sex and NIH risk categories.
RESULTS: Forty-six cases were categorised as GIST. Fifty percent were localised in the stomach, 43.5% in small intestine, 4.3% in the omentum, and 2.2% in colon. Thirty-seven percent were classified as high risk of an aggressive behaviour, 30.4% as intermediate risk and 32.6% as low or very low risk. Only one patient received treatment with imatinib mesilate. The annual incidence by 100,000 inhabitants in crude rate, European age-standardised rate and world age-standardised rate was, respectively, 1.09, 0.90 and 0.65 cases. The relative 5-year survival rate was 74.7% for the entire cohort, and it was markedly lower in the high-risk cases (20.3%).
CONCLUSIONS: We report the first population-based study of GIST incidence and survival in Southern Europe. The incidence rate is low and comparable with that of cancer registries from Northern Europe. Survival was favourable in our pre-imatinib population although it was low in high risk cases. Prognostic discrimination of the cases with intermediate, low, or very low risk is inadequate, and these categories should be considered jointly in the future. Our results will help researchers in establishing baseline values against which they can compare, in the future, the impact of imatinib and other Kit tyrosine inhibitors on survival.