When Are PARP Inhibitors Used to Treat Ovarian Cancer?

Studies show that taking a PARP inhibitor drug every day after surgery and chemotherapy can keep ovarian cancer at bay for longer, and extend the length of time before the cancer returns or gets worse.

Do You Need Maintenance Therapy?

PARP inhibitors do cause side effects. After undergoing major surgery and chemotherapy, both of which come with side effects and recovery time, it’s normal for women to be wary about immediately embarking on another round of treatment.

“Some people after the initial debulking surgery, where you have your uterus, your ovaries, and the cancer removed, followed by chemotherapy, are just kind of wiped out. They’ve had a lot of chemo, they’ve been through a lot. They’re adjusting to their new reality,” says Dr. John Nakayama, gynecologic oncologist at University Hospitals in Cleveland. “The question is, do you want to go on a pill?”

It’s important to answer that question as soon as possible because PARP inhibitors seem to have the most benefit when they’re given earlier. And although these drugs can cause side effects like nausea, vomiting, low blood cell counts, and fatigue, most people tolerate them pretty well, Dr. Nakayama says. PARP inhibitors, because they’re oral drugs, are also much easier to take than chemotherapy. “You don’t have to go into an infusion center,” Dr. Nakayama says.

Be open with your doctor about how you’re feeling while you take PARP inhibitors. At regularly scheduled appointments, discuss how the treatment is going, and whether you’re experiencing any side effects, so your medical team can address them.

Coming off treatment because of side effects can undo the gains you made during surgery and chemotherapy. “We know off of all the trials that we’re running, the odds are, if you don’t take that pill, the cancer is going to come back in five to six months,” Dr. Nakayama says.

What to Expect from Maintenance Therapy

It’s important to have realistic expectations when starting treatment with PARP inhibitors. With initial surgery and chemotherapy with drugs like carboplatin, your doctor was trying to remove as much of the tumor as possible and get your disease under control. This is the point where you and your doctor are hoping for a complete cure.

As its name suggests, maintenance therapy aims to keep the cancer from progressing, and postpone or even eliminate recurrences.

Once cancer does recur, doctors switch their thinking from curing the disease to treating it like a chronic condition to be managed. “Just like hypertension, you take a pill to keep your blood pressure under control. I like to think of the PARP inhibitor that way,” Dr. Nakayama says.

Women with BRCA1 or BRCA2 gene mutations seem to respond particularly well to PARP inhibitors, as do women with a homologous recombination deficiency (HRD). Having HRD means that your cancer cells already have trouble repairing themselves, a vulnerability that makes them even more responsive to treatments such as PARP inhibitors and platinum-based chemotherapy. Yet even women who don’t have these genetic changes can benefit from PARP maintenance therapy.

The American Society of Clinical Oncology (ASCO)  guidelines recommend 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.

Testing your tumor for BRCA and other genetic changes can determine whether you’re a good candidate for PARP inhibitors or other maintenance therapies. Genetic testing can guide your doctor to the most effective maintenance therapy strategy to keep your cancer in remission for as long as possible.

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