Incidence of 0.4-5.1% of nonmammary cancers identified in the breast.
Autopsy studies reveal an incidence of 1.7-6.6% incidence.
Metastatic lesions are primarily leukemia, melanoma, lung and prostate cancer.
Lesions are more likely to be mobile, well defined, round, solitary, and without pain, tenderness, skin alterations or nipple discharge than primary lesions.