Cancer that forms in tissues of the breast, usually the ducts (tubes that carry milk from lobules to the nipple). It occurs in both men and women, although male breast cancer is rare.
There are many different types of breast cancer. The type depends on which cells in the breast become cancerous. Breast cancer can begin in different parts of the breast, such as the ducts and the lobules mentioned in the NCI definition above.
According to the Center for Disease Control (CDC), the most common form of breast cancer is ductal carcinoma, or cancer that begins in the lining of the breast ducts. If these abnormal cancer cells remain only in the lining of the duct, it is referred to as ductal carcinoma in situ (DCIS). If they spread to invade the surrounding breast tissue, it is called invasive ductal carcioma. 7 out of 10 women with breast cancer have ductal carcinoma.
Another common form of breast cancer is lobular carcinoma, or cancer that begins in the lobules of the breast. Again, lobular carcinoma can be either in situ or invasive. 1 out of 10 women with breast cancer have lobular carcinoma.
Finding a lump in the breast or armpit is the most common way to detect cancer. However, the CDC reports that most breast lumps are not cancerous. Rather, the two most common causes for breast lumps are fibrocystic breast conditions and cysts.
The following additional symptoms listed by the CDC as possible signs of breast cancer can also be caused by conditions other than cancer:
If you have any concerns about your breast health, you should consult your doctor right away.