Common PARP Inhibitor Side Effects
- PARP inhibitors commonly have side effects like fatigue, nausea, and diarrhea
- Many of these problems may improve once you’ve taken these drugs for a while
- Doctors monitor for anemia and other potential issues from PARP inhibitors using lab tests
- Over-the-counter medications and prescription medications can help manage these symptoms
- Lowering the dose or going on a break from these drugs can lessen side effects without compromising treatment effectiveness
Most recently, the American Society of Clinical Oncology (ASCO) released new guidelines recommending PARP inhibitors be offered to women, with or without genetic mutations, who are newly diagnosed with stage III or IV ovarian cancer and have improved with chemotherapy.
Read MoreCommon Side Effects
Fatigue is one of the most common PARP inhibitor side effects, affecting more than half of the people who take these drugs. The tiredness that people experience while on these drugs can be even more severe than the more common chemotherapy-related fatigue.It’s also common for people who are on PARP inhibitors to have GI issues, such as:
- Nausea
- Indigestion
- Poor appetite
- Diarrhea
- Constipation
- Belly pain
PARP inhibitors interfere with cells' ability to repair their damaged DNA. That's good when it comes to cancer cells, but it can cause problems when it affects blood cells. Damage to bone marrow (where new blood cells are made) can lead to a drop in oxygen-carrying red blood cells (called anemia), as well as a reduction in infection-fighting white blood cells. This treatment can also damage platelets, which help the blood to clot.
Individual PARP inhibitor drugs have their own, specific side effects. For example, niraparib (brand name Zejula) can cause an irregular heart rhythm or high blood pressure. rucaparib (brand name Rubraca) and olaparib (brand name Lynparza) may affect both liver and kidney function.
Monitoring for Side Effects
Your doctor will carefully monitor you for side effects throughout your treatment, especially your blood cell count. You may get lab tests every week for the first month you're on these medications, which are done "to make sure that they’re not becoming anemic or their platelets are not becoming too low," Dr. Engle says.
Blood tests can also reveal whether you have low hemoglobin levels, which could contribute to fatigue. Anemia and fatigue could be signs that you need an adjustment in your medication dosage, or a switch to a different PARP inhibitor drug. If your blood cell counts remain stable over the first month of treatment, your doctor may stretch out the testing to once a month.
There are effective ways to manage some of these side effects. For example, if nausea is a problem, taking an anti-nausea medication before your PARP inhibitor may help. Taking good care of yourself is also a good strategy. Regular exercise even a daily walk can help combat fatigue. Eating a nutritious diet with adequate amounts of protein will help replenish damaged blood cells. Meditation and other relaxation techniques can improve nausea and vomiting.
An End to Side Effects in Sight
The good news is that PARP inhibitor side effects are generally short-lived. Eventually, your body will become acclimated to the medication. "Many of these side effects will disappear or dissipate over time," Dr. Engle says. Usually within four to six weeks after you start treatment, you'll see an improvement. "The body just kind of gets used to this as the new normal, and those symptoms will start to abate."
It's important if you take PARP inhibitors, or any other ovarian cancer treatment for that matter, to be open with your doctor about how you’re feeling. Let your doctor know about any side effects you experience, especially ones that are uncomfortable or that don't improve. There may be an option to manage your symptoms and make you feel better.
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