Estrogen receptor positive is the most common form of breast cancer - around 80% of breast cancers are ER-positive.

Breast cancer cells that do not have estrogen receptors are known as estrogen-receptor-negative (or ER-negative) cancers.

People who have had breast cancer in the past are at higher risk for developing other types of cancers. Learn more about why.

While smoking is a risk factor for all types of cancer, it is significantly associated with breast cancer in women.

Women with large, dense breasts who undergo repeated mammography may be at higher risk for radiation-induced breast cancer.

A study published in the Journal of National Cancer Institute in 2001 reported that women who work in rotating night shifts for at least three nights per month, along with day shifts, have a moderately high risk of breast cancer.