Frequent allelic losses at 11q24.1-q25 in young women with breast cancer: association with poor survival.

Previous studies have demonstrated that the pathological features of breast cancer are more aggressive in younger women than in their older counterparts, and that young age may be an independent marker for adverse prognosis. These findings have raised the question whether these differences are also present at the molecular level. In order to characterize the genetic alterations associated with early-onset breast cancer, 102 cases selected for age under 37 at diagnosis were examined for loss of heterozygosity (LOH) at nine different loci on chromosomes 11, 13 and 17. Ninety cases (88%), exhibited LOH for at least one marker. The D17S855 marker, intragenic in the BRCA1 gene, showed a high proportion of LOH (63%), whereas the intragenic marker for the TP53 gene, HP53, exhibited LOH in 43% of the cases. On chromosome 11, frequencies of LOH peaked at the D11S969 and D11S387 markers, which expressed LOH in 53% and 48% of the informative cases, whereas D11S1818, which is proximate to the ATM gene, exhibited an LOH frequency of 24%. A statistically significant correlation was found between LOH at the D11S387 marker and poor survival (P = 0.028). No such correlation was found for the adjacent D11S969 marker, located approximately 500 kb centromeric to D11S387. We conclude that one or more as yet unidentified genes, situated in chromosome bands 11q24.1-q25, could be involved in the initiation and/or progression of breast cancer in younger women.