Common cytogenetic findings in primary breast cancer.

Five cases of breast cancer were cytogenetically studied by G-banding, using direct tumor preparations. Chromosomes involved in aberrations, according to frequency, were #1, #11, #3, #6, #5, and #17. In all five cases there were abnormalities of chromosomes #1 and #11. In each case chromosome #1 was involved in at least two different ways. In four cases abnormalities of chromosomes #11 exhibited nonrandom involvement of band q22-23. These findings confirm the role of chromosomes #1 and #11 in breast cancer and show that band 11q22-23, which has been reported to be an inheritable fragile site and is a specific breakpoint in acute leukemia, also may be specific in a group of breast cancer. Thus, correlation of an inheritable fragile site and a malignant disease with familial incidence seems possible.