Finding the five-year window: A qualitative study examining young women's decision-making and experience of using tamoxifen to reduce BRCA1/2 breast cancer risk.

Objective: Tamoxifen has been demonstrated to reduce breast cancer risk in high-risk, premenopausal women. Yet, very few young women with hereditary breast and ovarian cancer syndrome in Australia use tamoxifen, despite this being a less-invasive option compared to risk-reducing mastectomy. This study aims to examine young women's decision-making about and experience of taking tamoxifen to reduce their breast cancer risk.

Methods: Young women with a BRCA1/2 mutation participated in semi-structured qualitative interviews, recruited mainly from a metropolitan clinical genetics service. Data were analysed using an inductive, team-based approach to thematic analysis.

Results: Forty interviews with women aged 20-40 years with a BRCA1/2 mutation were conducted. Eleven women could not recall discussing tamoxifen with their healthcare provider or were too young to commence cancer risk management. Twenty-three women chose not to use tamoxifen because it is contraindicated for pregnancy or because it did not offer immediate and great enough risk reduction compared to bilateral risk-reducing mastectomy. Six women who were definite about not wanting to have children during the following 5-year period chose to use tamoxifen, and most experienced none or transient side effects.

Conclusions: Decision-making about tamoxifen was nuanced and informed by considerations characteristic of young adulthood, especially childbearing. Therefore, clinical discussions about tamoxifen with young women with a BRCA1/2 mutation must include consideration of their reproductive plans.