Coexistence of gastrointestinal stromal tumors (GIST) and malignant neoplasms of different origin: prognostic implications

BackgroundOver past decade, several changes occurred in diagnostics, treatment and understanding of pathogenesis of gastrointestinal stromal tumors (GIST). However, their coexistence with other malignancies of different histogenetic origin remains challenging issue. MethodsGIST-patients in 10-years period were identified retrospectively, clinical history and findings thoroughly explored for presence of associated malignancies and prognostic implications were investigated. Results Thirty seven (M:F=27:10) of 86 GIST-patients (43%) had another malignancy. Mean age was 70 years. Associated malignancies were gastrointestinal (n=29;69%), renal-/urological (n=5;12%), haematological (n=4;9.5%), cutaneous (n=3;7%) and thyroid (n=1;2.5%) in origin. Majority of GIST occurred in stomach (65%) and small intestine (30.6%) and most (78%) were asymptomatic incidental findings during diagnostic/therapeutic procedures for associated malignancies. Mean size was 2.2cm (range:0.1-9) and all of them had no/low mitotic activity. Thirty one tumors (84%) were of no/very low/low and 6 were of intermediate risk. During follow-up (range:3-160months, mean:60months), one patient suffered from distant metastases of GIST. Seven patients died of associated malignancies and three patients of other non-tumor-associated cause, but none died of GIST.ConclusionCoexistence of GIST with other malignancies is higher than previously reported and should draw attention of clinicians towards these incidental findings. Prognosis is usually determined by other malignancy and not significantly influenced by GIST. Therefore treatment algorithms should be focused on prognostically relevant malignancy.