Breast
cancer is a disease where cells inside breast grow out of control. There are distinct types of breast cancers, classified by which area of breast
it has occurred. Though
breast cancer can occur in both, male and female, but women are more likely to
have it. This cancer is the most common cancer among women. The cancer can spread outside the breast through blood
vessels and lymph vessels. When breast cancer spreads to other parts of the
body, it is said to have metastasized.

Breast cancer can occur at any age, race or sex. There are various causes and risk factors of breast cancer. Some of them are –
References:
Breast cancer - Symptoms and causes - Mayo Clinic