Gastrointestinal stromal tumor associated with other primaries: A study of 154 patients

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10567 Background: The objective of this study is to investigate the characteristics and survival rate of patients with Gastrointestinal Stromal Tumor (GIST) associated with other primary malignancies. Methods: 783 patients with GIST were treated at M. D. Anderson Cancer Center from 1995 to 2007. Multiple primaries included tumors that were not considered to be a metastasis, invasion or recurrence of GIST excluding non-melanoma skin cancer. Data on gender, age at diagnosis of cancer, follow-up time after diagnosis, and death rate were collected. Results: Of the 783 patients, 154 (20%) were identified with at least one other primary other than GIST (GIST+). The ratio of men and women was 1.5 and 1.3 in patients with GIST+ compared to those with GIST only, respectively. Median age at diagnosis of GIST was 57 for patients with GIST only whereas it was 68 in patients with GIST+. The stomach was the frequent site of occurrence in GIST only and GIST+. The total numbers of other primaries developed before the diagnosis of GIST was higher (134) than the primaries developed after the diagnosis of GIST (53). The most frequent primaries observed before the diagnosis of GIST were prostate (25), breast (12), esophagus (9), kidney (7) and melanoma (6). Lung (5) and kidney (5) were the most frequent type of primaries that developed after the diagnosis of GIST. The 5-yr survival was 68% for patients with GIST+ when the other primary occurred before GIST, 61% for patients with GIST+ when the other primary occurred after the diagnosis of GIST, 58% for patients with GIST only, and 49% for GIST++ patients with two or more other primaries (p=0.002). Conclusions: Superior survival in GIST+ patients may be due to the bias of early detection. The etiology and clinical implications of the association of other primaries in GIST patients should be further investigated. No significant financial relationships to disclose.