OBJECTIVETo investigate the clinicopathological significance of chromosome 17 polysomy in breast cancer.

METHODSRetrospective study of 200 cases of breast cancer including 106 cases of invasive ductal carcinoma and 94 cases of in-situ carcinoma was performed by fluorescence in-situ hybridization (FISH) to explore the relationship between chromosome 17 polysomy and age, nuclear atypia, lymphatic metastasis, HER2 gene amplification and HER2 protein expression.

RESULTSTwenty-six percent (52/200) of chromosome 17 polysomy was detected in 200 cases of breast ductal carcinoma, all of which were invasive ductal carcinoma. Overall 52. 8% (52/180) of invasive ductal carcinoma cases showed chromosome 17 polysomy, which was correlated to HER2 gene amplification (P = 0.000) and HER-2 protein expression (P=0.000), and to HER2 expression combined with HER2 gene amplification (P=0.001). Chromosome 17 polysomy with or without HER2 gene amplification was also associated with high-grade nuclear atypia (P = 0.012 or P = 0.010) and lymphatic metastasis (P = 0.002 or P = 0.009 ). However, chromosome 17 polysomy with or without HER2 gene amplification was not correlative with the age of patients (P = 1. 000 or P = 0. 415).

CONCLUSIONChromosome 17 polysomy may be related to the nuclear atypia, metastasis, HER2 gene amplification of invasive ductal carcinoma and thus a worse prognosis of the patients.