Individuals who have previously had breast cancer should not use estrogen as part of gender-affirming care due to the potential risks associated with hormone-sensitive cancers. Estrogen therapy, a key component of feminizing hormone therapy, can stimulate the growth and proliferation of hormone-sensitive breast cancer cells, which can increase the risk of cancer recurrence or progression. Therefore, individuals with a history of breast cancer are advised against estrogen therapy to prioritize their long-term health and reduce the likelihood of cancer recurrence.
