How is breast cancer transmitted?

It's not: Breast cancer is not transmitted from one person to another. It starts as a normal cell in the breast. The cell is damaged and instead of dying, it starts dividing, making more damaged cells that also divide. That's breast cancer in a nutshell... Breast cells that keep dividing and don't stop.

Lymphatic System: Breast cancer cells travel through the body via the lymphatic system. The lymphatic system is a series of vessels that drain lymphatic fluid throughout the body. Lymph nodes are lima bean sized organs that filter the fluid for foreign particles and cancer cells. A sentinel lymph node is the first lymph node to which a cancer spreads.