Poly ADP-ribose polymerase (PARP) inhibitors are a type of cancer treatment that prevents cancer cells from repairing themselves, which causes the cells to die. They’re currently used to treat ovarian cancer that has come back after initial treatment.
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In this article, we’ll take a deeper look at PARP inhibitors, what they are, and how they’re used to treat ovarian cancer.
PARP, or poly ADP-ribose polymerase, is an enzyme. Cells use PARP to repair their DNA when they become damaged by things such as radiation, ultraviolet (UV) light, and cancer treatments.
A PARP inhibitor is a targeted medication that prevents the PARP enzymes in cancer cells from working correctly. This stops the cancer cells from repairing themselves during cancer treatment and causes the cancer cells to die.
According to Cancer Research UK, PARP inhibitors are currently used in the treatment of:
- ovarian cancer
- fallopian tube cancer
- peritoneal cancer
- breast cancer
- metastatic prostate cancer
- pancreatic cancer
Clinical trials are being done to see how they might benefit other cancers as well.
PARP inhibitors are most often used to treat advanced ovarian cancer that has come back after first round treatment. They can be used alone or after other treatments such as radiation therapy or chemotherapy.
They’ve also been approved as maintenance therapy for some types of ovarian cancer. Maintenance therapy is therapy given after initial treatment has cleared your body of cancer. It is used to prevent the cancer from coming back.
PARP inhibitors are still a new treatment for ovarian cancer. Researchers are still learning when and how to use them best.
As more data continues to come in, it’s likely that standard treatment for ovarian cancer will more often include earlier use of PARP inhibitors.
According to a 2020 review, PARP inhibitors are most effective, and their role is most well established, in people with ovarian cancer who have a mutation on the BRCA1 or BRCA2 gene. These genes are used to repair cells in the body. People with mutations on these genes are at an increased risk of ovarian, breast, and prostate cancer.
The cancer cells of people with mutations on the BRCA1 or BRCA2 gene already have a weak repair system. When a PARP inhibitor further blocks that repair system, the cancer cells have no ability to repair themselves. This kills the cancer cells. A
Certain PARP inhibitors, such as niraparib (Zejula), have also been shown to be effective outside of the BRCA mutation populations. PARP inhibitors are not as effective in treating ovarian cancer not caused by BRCA mutations. But a
There are a few side effects to PARP inhibitors. They can affect your liver and kidney. You’ll have regular blood tests while you take them to monitor this possible side effect. Most other side effects are mild, but it’s a good idea to mention them to a medical professional if they occur.
Side effects can vary slightly between the three different types of PARP inhibitors available for ovarian cancer: olaparib (Lynparza), niraparib (Zejula), and rucaparib (Rubraca).
The most common side effect is fatigue. Other potential side effects include:
- increased infections
- increased bleeding
The typical first treatment for ovarian cancer is surgery to remove cancerous tissue and organs. The exact surgery will depend on how far cancer has spread.
A complete hysterectomy is recommended in most cases. However, if the cancer is found early and is only in one ovary, you might be able to have only the affected ovary and fallopian tube removed. Your doctor will discuss your options with you.
Following surgery, you’ll have additional treatments to kill any remaining cancer cells. These might include:
Have a discussion with your doctor about treatment options
You and your doctor can discuss your treatment plan and decide what’s best for you. It’s a good idea to ask questions and make sure you fully understand your options before you commit to a treatment plan. Consider asking your doctor the following questions:
- What is the stage of my ovarian cancer?
- What is my individual outlook?
- Will I need to have surgery and what will that involve?
- How will my surgery affect my ability to have children?
- What additional treatments do you recommend following surgery?
- What side effects should I expect from these treatments?
- What are all my potential treatment options?
- What will happen if I don’t pursue treatment right away?
- Should I (or my children) have genetic testing, since BRCA mutations are inherited?
PARP inhibitors are a promising treatment for ovarian cancer. They work by blocking an enzyme that cells use to repair DNA damage. They can be used as a cancer treatment by stopping cancer cells from repairing themselves, which kills the cancer cells.
Research shows that PARP inhibitors are very effective at increasing lifespan and preventing cancer relapse for people with ovarian cancer, especially those with abnormalities on the BRCA1 or BRCA2 gene. Studies show they might also be effective for other people with ovarian cancer, and for people with additional types of cancer.