Hormonal contraception and breast cancer

The recent Danish cohort study reported a 20% increased risk of breast cancer among current and recent hormonal contraception users. These results are largely consistent with previous studies. This study did not report on stage of disease at diagnosis and it is not clear to what extent the apparent increased risk may be due to a small advance in the timing of diagnosis. This study did not report on the risk associated with the use of a 20-mg ethinyl estradiol pill. They did find an increasing risk in current users of longer duration and an increased risk with use of the levonorgestrel intrauterine system-both of these potentially important findings have not been consistently found in previous studies and require further investigation. The breast cancer effects described now in multiple studies wane with time, and in the long-term hormonal contraception use has been found not to be associated with any increased total cancer risk.