Prognostic importance of cell-cycle activity and genotype in gastrointestinal stromal tumors

e20501 Background: Size, mitosis and locus are important for risk stratification of gastrointestinal stromal tumors (GIST). Genotype and cell cycle are suggested related to aggressiveness and progression, and considered to have prognostic impact, although most reports have analyzed expression of proteins or mRNAs. In this study, we examined the biological and prognostic values of CDK activities in primary GIST with R0 surgery. Methods: Histologic Dx was done with HE and IH. Using lysate of frozen materials from 76 pts with GIST (n=70), leiomyoma (2), schwannoma (3) and abdominal sarcoma (1), CDK-specific activities were measured by the C2P system (activities of CDK1 & CDK2). The median age was 64 yrs and 33 (45%) pts were male. The median follow-up was 37 months. Results: KIT and PDGFRA mutations were found in 57 and 7 GIST pts, respectively, and deletion of codon 557-558 in 16 pts. Two pediatric GISTs and one with NF-1 had no mutation in both genes. CDK activities were measurable in 63 (86%) pts, and med...