What is the difference between breast cancer and a tumor?

Terms: All tumors are growths that result from mutated genes. Cancers are tumors in which the genome has not only mutated but become destabilized, giving the power to evolve into invasive forms. Many tumors are quite benign, in distinction from cancer. This is a common point of confusion even among student doctors, and is a very good question.

Definitions: A tumor is a general term for a lump or mass in any location in the body. It can be cancerous or noncancerous. Breast cancer refers to malignant cells found in the breast. There are many benign/noncancerous tumors that can be found in the breast. Usually a needle biopsy is performed to determin if cancer is present.