List of known risk factors

Here is a table listing of the different categories of known risk factors:Weak risk factors for breast cancer
Family history of postmenopausal breast cancer, except if associated with male breast cancer + bilateral disease
High Socioeconomic status
Nulliparity
Later age at first birth (30 yr vs. 20 yr)
Later age at menopause (55 yr vs. 45 yr)
Early age at menarche (11 yr vs. 15 yr)
Postmenopausal obesity
Alcohol consumption
Diet
Hormone replacement therapy (long term usage)

Moderate risk factors for breast cancer Older age
North American and Northern European residence
Family history of premenopausal breast cancer
Personal history of breast cancer
Breast hyperplasia without atypia
Mammographic density occupying 50% of the breast volume

Strong risk factors for breast cancer
Family history of premenopausal bilateral breast cancer or premenopausal breast cancer in mother, grandmother, sister, daughter and aunt or breast cancer and ovarian cancer in mother, grandmother, sister, aunt
Evidence of susceptibility gene BRCA1/BRCA2
Personal history of lobular carcinoma in situ
Breast atypical hyperplasia
Mammographic density occupying 75% of the breast volume