A virus that infects humans without causing disease kills breast cancer cells in the laboratory. Researchers from Pennsylvania State University (Penn State) College of Medicine in the US, tested an unaltered form of adeno-associated virus type 2 (AAV2) on three different human breast cancer types representing different stages of cancer and found it targeted all of them...

But research with minority women doesn't prove cause-and-effect

Alcohol is known to be carcinogenic to humans in the upper aerodigestive tract, liver, colorectum, and the female breast. Evidence suggests that acetaldehyde, the primary metabolite of alcohol, plays a major role in alcohol-related esophageal cancer...