How Does Olaparib Work? — The PARP Inhibitor Explained

For most of its approved uses, yes — a BRCA mutation or a similar fault in the same repair pathway is what makes your cancer cells vulnerable to olaparib's mechanism. This is why testing was done before the prescription. Without that specific weakness, blocking PARP alone does not have the same effect. For some cancer types, approvals also cover tumours with broader HRD faults rather than a BRCA mutation specifically. Your oncologist can explain which criterion applies to your situation.

Olaparib is taken as a tablet by mouth, usually twice a day. It does not need to be given as an infusion in a clinic. You collect it from the pharmacy and take it at home on the schedule your team gives you. Some medicines can affect how olaparib is absorbed or processed by the body, so tell your team about everything you are taking — including supplements and traditional remedies — before you start and throughout treatment.

The duration depends on your cancer type, stage, and whether olaparib is being used as maintenance treatment after chemotherapy or as active treatment for returning or advanced disease. Maintenance use typically continues until the disease starts growing again, or for a period defined in the approval for your specific situation. Your oncologist will set a treatment plan with scheduled review points and explain the intended duration at each stage.

We avoid the word cure when explaining what olaparib aims to achieve, because it is not accurate for most situations where it is prescribed. Used as maintenance after chemotherapy, it is intended to delay the cancer from returning or growing. Used as active treatment, it aims to control the cancer for as long as possible. What that means in terms of time varies between individuals. Asking your oncologist directly what the goal of treatment is for your specific situation will give you a clearer and more honest answer than any general statement.

The most commonly reported side effects are nausea, fatigue, and anaemia — a drop in red blood cells that can make you feel tired or short of breath. Blood counts are monitored regularly for this reason. Nausea often settles after the first few weeks, but tell your team if it is affecting your ability to eat, because there are medicines that help. A less common but more serious side effect is myelodysplastic syndrome, a blood disorder — your team watches for this with routine monitoring.

It depends on where your BRCA mutation was found. If it was in a blood test, it is a germline mutation — one you were born with and could have passed on to children, or inherited from a parent. In that case, blood relatives may benefit from genetic counselling and testing. If the mutation was found only in tumour tissue and not in blood, it is somatic — it developed in the cancer, not inherited — and family testing is less urgent. A genetic counsellor can advise which applies to you and guide any next steps for your family.