PURPOSE: To describe the use of hormonal contraceptives in Danish breast cancer patients.

METHODS: Nationwide drug utilization study in Danish women diagnosed with breast cancer at ages 13-50 years during 2000-2015. User proportions were estimated in 6-months intervals from 2 years before to 2 years after diagnosis.

RESULTS: Use of hormonal contraceptives declined sharply after breast cancer diagnosis. Still, 7% of patients aged 13-39 years filled hormonal contraceptive prescriptions within 6 months after the diagnosis.

CONCLUSIONS: The majority of premenopausal breast cancer patients discontinues hormonal contraception at diagnosis. All prescribers of hormonal contraceptives should acknowledge that hormonal contraception is contraindicated for breast cancer patients.

PLAIN LANGUAGE SUMMARY: Use of hormonal contraception is contraindicated among women with breast cancer. In this nationwide study, we assessed the use of hormonal contraceptives among all Danish premenopausal women diagnosed with breast cancer during 2000-2015. Hormonal contraceptive use was assessed within 2 years before and 2 years after breast cancer diagnosis. The majority of patients discontinued hormonal contraception at breast cancer diagnosis. However, 7% of patients aged 13-39 years filled hormonal contraceptive prescriptions within 6 months after the diagnosis.