Oral contraceptive use and breast cancer risk in young women: subgroup analyses. UK National Case-Control Study Group.

Abstract

The UK National Case-Control Study Group reported an increased risk of breast cancer associated with oral contraceptive (OC) use in women in whom the disease was diagnosed before the age of 36. In further analyses to ascertain whether any subgroup is at particularly increased risk, women were grouped by age at diagnosis, reproductive history, personal habits and characteristics, family history of breast cancer, and history of biopsy for benign breast disease; these subgroups were also defined by overall risk score. There was little evidence of altered risk in relation to subgroups: women with a family history of breast cancer had a slightly greater risk associated with OC use than those without, but the difference in trends was not significant.