Modern medical risks:

Early and prolonged use of oral contraceptives.

Oestrogen replacement therapy, with high doses and prolonged use.

Premenopausal mammography, with early and repeated exposure.

Non hormonal prescription drugs, such as some anti hypertensive drugs.

Silicone gel breast implants, especially those wrapped in polyurethane foam.

Dietary and environmental risks:

Diet high in animal fat, contaminated with undisclosed carcinogens and oestrogenic chemicals.

Exposure to household chemicals or pollution from neighbouring chemical plants and hazardous waste sites.

Workplace exposure to a wide range of carcinogens.

Lifestyle risks:

Alcohol, with early or excessive use.

Tobacco, with early or excessive use.

Inactivity and sedentary lifestyle.

Dark hair dyes, with early or prolonged use.