Letrozole and estrogen: what should you know?

Letrozole is an aromatase inhibitor. It reduces the conversion of other hormones into estrogen, mainly after menopause. Lower estrogen signalling can slow stimulation of some hormone-sensitive breast cancer cells. It does not remove estrogen from every source in the body, and it is not suitable for every person or every cancer.

Lower estrogen can also affect healthy tissues. Hot flushes, night sweats, vaginal dryness, lower sexual interest, tiredness, mood changes, and joint or muscle aches may occur. Longer treatment can affect bone strength, so your team may review bone health and other medicines.

Take letrozole exactly as prescribed and keep a record of new symptoms. Do not stop it or add hormone products, supplements, or other medicines without checking first. Tell the team about previous fractures, bone conditions, liver problems, cholesterol concerns, and all medicines you take.

Gentle movement, strength-building activity suited to your health, adequate calcium and vitamin D from food or prescribed supplements, and practical measures for hot flushes may help. Your clinician can decide whether you need blood tests, a bone density assessment, or a change in treatment.

Contact your oncology team promptly for severe or persistent joint pain, a new fracture, marked weakness, yellowing of the skin or eyes, dark urine, unusual bleeding, or symptoms that make daily activities difficult. Seek urgent help for chest pain, sudden breathlessness, one-sided weakness, facial swelling, or signs of a serious allergic reaction.

Ask why letrozole is recommended for your cancer, how long the planned course may be, how estrogen-related symptoms can be managed, whether your bones need monitoring, and which medicines or supplements should be avoided.