Adjuvant Olaparib — After Early Breast Cancer Surgery

Nausea, fatigue, and a low red blood cell count (anaemia) are the side effects reported most often in clinical trials of olaparib. Nausea tends to be more noticeable in the first weeks and improves for many patients as treatment continues. Fatigue can be significant — tell your team if it is affecting your daily life, because there may be things that help. Your blood counts will be checked regularly because anaemia is a known and expected effect. A rare but important risk is myelodysplastic syndrome or acute myeloid leukaemia, which your team will watch for over time. Report any new symptoms promptly rather than waiting for your next scheduled appointment.

Olaparib is taken as tablets by mouth, twice a day, every day — not administered by IV at a clinic. Most patients take it with or without food, though taking it with food can help if nausea is a problem. NCCN and ESMO guidelines specify a total treatment duration of one year for the adjuvant setting, based on the clinical trial that established this use. Your oncologist will set your start and end dates and will review you at intervals throughout. Do not stop taking olaparib without speaking to your team first, even if you feel well — completing the full course is part of how the treatment is intended to work.

Regular blood tests are a standard part of adjuvant olaparib treatment. Your team will check your full blood count — including red cells, white cells and platelets — at intervals they specify based on your situation. If your haemoglobin drops significantly, your team may adjust the dose, pause treatment temporarily, or recommend iron supplements or other support. You will also have periodic clinical review appointments to assess how you are tolerating the drug. Bring a record of any new symptoms since your last appointment, including ones that seem unrelated to treatment, because olaparib can affect several organ systems.

Olaparib should not be taken during pregnancy. It can cause harm to a developing baby based on how the drug works at a cellular level. Effective contraception is required throughout treatment and for a period after finishing — your oncologist will specify exactly how long. If pregnancy is something you want to consider in the future, discuss fertility preservation before starting olaparib, and ideally before chemotherapy begins. Egg or embryo freezing may be an option depending on your situation and timing. Your team can refer you to a fertility specialist if this conversation has not already happened.

If you miss a dose, do not double up at the next time — take your next scheduled dose as normal and carry on. If you vomit shortly after taking a dose and are unsure whether it was absorbed, call your team for guidance rather than taking an extra tablet on your own judgement. Temporary pauses are sometimes needed — for example if your blood counts fall outside a safe range — and your oncologist manages those decisions and determines when it is safe to restart. If side effects are making it hard to continue, speak to your team before stopping permanently. There are often options to manage side effects before discontinuing the drug entirely.

Yes — olaparib has known interactions with a number of medicines processed through the same liver enzymes, including certain antifungal tablets, some antibiotics, and some medicines used for mood disorders. These interactions can significantly raise or lower the level of olaparib in your blood. Herbal products are also included in this warning: St John's Wort, for example, can reduce olaparib's effectiveness. Tell your oncologist and your pharmacist about everything you take — prescription medicines, over-the-counter medicines, supplements and herbal preparations. Your team may need to adjust other medicines during the time you are on olaparib, rather than changing the olaparib dose itself.