ras and p53 genes in male breast cancer.

We have studied the roles of Ki-ras oncogene and p53 tumor suppressor gene in a series of 20 cases of male breast cancer and one papilloma of the male breast. Ki-ras was detected in 50-microns sections after digestion with proteinase K and SDS. DNA was amplified by polymerase chain reaction, dot blotted, and mutations were screened with labeled ras mutation-specific oligonucleotides. Wild-type and mutant p53 protein were detected with antibodies CM1 and DO7, using the avidin-biotin-peroxidase method. Two of 17 carcinomas showed Ki-ras mutations, both in codon 12 (gly --> lys and gly --> arg). Five of 20 male breast cancers (25%), including one large intraductal carcinoma, expressed mutant p53 protein. Although the incidence of mutant p53 expression in male breast cancer is similar to that in women, Ki-ras mutations are not significantly increased.