Introduction

Breast cancer (BC) is the most common cancer in women worldwide. Although it is more common in older women, it is increasingly being diagnosed in premenopausal women.1 During BC treatment and some time after treatment is complete, avoiding pregnancy is recommended. BC outcomes could be adversely affected by pregnancy itself or by delayed treatment due to pregnancy, and treatment could be teratogenic.2 Many women with BC remain sexually active throughout treatment and may continue to be fertile and at risk of pregnancy. It is therefore essential to support these individuals to make informed choices about safe, effective contraception.

The Faculty of Sexual & Reproductive Health (FSRH) Clinical Effectiveness Unit (CEU) has published guidance for clinicians on ‘Supporting Contraceptive Choices for Individuals Who Have or Have Had Breast Cancer’.2 Initially the CEU hoped that review of the published evidence would inform how different hormonal contraceptives affect BC outcomes, depending on the characteristics of the BC and its treatment. There is not, however, robust, direct published evidence to inform the effect of use of hormonal contraception (HC) on outcomes following a diagnosis of any BC. The guidance around suitability of hormonal contraceptives is based, therefore, on consensus opinion of breast and sexual and reproductive health (SRH) experts, supported by very limited indirect evidence.

The guidance2 highlights other key considerations – contraceptive effectiveness, drug–drug interactions, comorbidities (related and unrelated to BC) and factors that can affect acceptability (eg, bleeding patterns, side effects, non-contraceptive benefits) – that may influence contraceptive choice.