History of in situ or invasive breast cancer increases risk: Risk of developing cancer in the contralateral breast after mastectomy is about 0.5 to 1%/yr of follow-up.

• 原位或浸润性乳腺癌史增加癌症危险。乳房切除后，随访病人中对侧乳房的癌症危险率约0.；5-1%25/年。