The result is what we call invasive breast cancer.
Chemotherapy is never used for non-invasive breast cancer, since this type of cancer does not spread beyond the breast.
Systemic treatment may benefit some women who have invasive breast cancer without lymph node involvement.
In non-invasive breast cancer, cells grow too much but haven't started to invade normal surrounding healthy tissue.
Participants were assessed at regular intervals from 1980 until 2008 to record alcohol intake and cases of invasive breast cancer, among other things.
