PARP inhibitors for BRCA-mutated breast cancer

PARP inhibitors are targeted tablets that work particularly well in breast cancers linked to inherited changes in the BRCA1 or BRCA2 genes. The two used in breast cancer are olaparib and talazoparib. Cancer cells with a faulty BRCA gene already struggle to repair damaged DNA. PARP inhibitors block a second repair route, so the cancer cells cannot fix their DNA and die, while healthy cells, which still have a working BRCA repair system, are much less affected. They are used in HER2-negative metastatic breast cancer in people with a BRCA mutation, and olaparib is also used after surgery for some high-risk early breast cancers in BRCA carriers.

Why a genetic test matters

PARP inhibitors are only effective for people with an inherited BRCA1 or BRCA2 mutation, and sometimes certain other gene changes. Genetic testing, usually a blood test, is needed before treatment can be considered.

How they compare with chemotherapy

In metastatic BRCA-related breast cancer, PARP inhibitors controlled the cancer for longer than standard chemotherapy in studies, and many people found them easier to live with, though they have their own side effects.

Who they may not suit

People without a relevant gene mutation, those with significant bone marrow problems, and pregnant women. Your oncologist will check your blood counts and history before starting.

For people with BRCA-related breast cancer, PARP inhibitors are a genuinely targeted option. In metastatic disease they can control the cancer for a meaningful time, though they do not make it go away for good, and cancers can eventually become resistant.

Only a minority are eligible

Inherited BRCA mutations are found in a small share of breast cancers, more often in younger women, triple negative cancers, and those with a strong family history. Many people will not qualify.

Blood counts need close watching

Low haemoglobin is the most common reason for dose changes. Regular blood tests allow early adjustments.

Rare long-term risks

A small number of people develop bone marrow disorders. Your team monitors blood counts to detect problems early.

What this page cannot tell you

It cannot tell you whether you carry a relevant mutation or would benefit. Ask your oncologist about genetic testing.

PARP inhibitors are taken at home, which many people appreciate, but they still need a careful routine.

Taking tablets correctly

Take doses at the same times each day. Swallow tablets whole, and avoid grapefruit and some medicines that interact.

Managing sickness and tiredness

Small, frequent meals, anti-sickness medicine and gentle activity help. Rest when needed and pace your day.

Regular blood tests

Tests are usually monthly, more often at the start. Keep appointments even when you feel well.

For BRCA carriers with HER2-negative metastatic breast cancer, a PARP inhibitor may be offered at different points in treatment.

Triple negative cancers

A PARP inhibitor can be an option instead of chemotherapy, often after earlier treatments.

Weighing it against chemotherapy

Your oncologist compares the likely benefit, side effects and practical differences, such as tablets at home versus infusions, so you can choose together.

Hormone-sensitive cancers

It is usually considered after hormone treatments, including CDK4/6 inhibitors, have stopped working.