Aberrations of chromosome 13q in gastrointestinal stromal tumors: analysis of 91 cases by fluorescence in situ hybridization (FISH).

The clinical behavior of gastrointestinal stromal tumors (GISTs) ranges from benign to malignant. Recent studies suggest that loss of 13q could be correlated with GIST progression. Our objectives were: (1) to detect chromosome 13q aberrations and determine the corresponding gene status in GISTs; and (2) to assess potential roles of 13q aberrations in GIST by correlating various 13q aberrations with various histologic parameters and disease-free survival in a group of GIST patients. Ninety-one cases of primary GISTs in Chinese patients were studied by dual color fluorescence in situ hybridization (FISH), through use of a panel of bacterial artificial chromosome clones RP11-685I15, RP11-352N7, and RP11-505F3 covering the Rb, RFP2, KCNRG, and KLF5 genes, respectively. Loss of RP11-685I15 was detected in 17/91 (18.7%) cases, loss of RP11-352N7 in 11/91 (12.1%) cases, and loss of RP11-505F3 in 5/91 (5.5%) cases. Chromosome 13 polysomy was observed in 22/91 (24.2%) cases. The frequency of RP11-685I15 deletion was positively correlated with tumor risk (P=0.0460). The frequency of RP11-352N7 deletion, RP11-505F3 deletion, and chromosome 13 polysomy tended to be higher in the high-risk GISTs. Shorter disease-free survival was significantly associated with RP11-352N7 deletion (P=0.0361) and high-risk grade (P=0.0003). Chromosome 13 instability of GISTs may play a role in tumor progression. Loss of 13q, especially loss of Rb, RFP2, KCNRG, and KLF5 genes are frequent events in high-risk GISTs. Loss of 13q may be associated with tumor progression.