Loss of heterozygosity of the L-myc oncogene in human breast tumors.

Recent studies suggest that loss of heterozygosity may play an important role in various human neoplasia. Cytogenetic abnormalities detected in primary breast tumors led us to examine breast tumor DNAs for deletions. In the present study, we demonstrate, using restriction fragment length polymorphism (RFLP) analysis at the L-myc proto-oncogene (chromosome 1p32), a frequent loss of heterozygosity in primary breast tumor DNAs (55 out of 152 informative tumor DNAs). Most of these deletions appear to be limited to chromosome 1p. No correlation was observed between this genetic alteration and several parameters of each patient's history or characteristics of the tumor. However, a significantly (P = 0.011) shorter survival period after relapse was observed for patients with loss of heterozygosity at L-myc in primary tumor DNAs compared with patients with tumor DNAs lacking this alteration.