Homologous Recombination Deficiency: What is it And Why It Can Matter For Your Treatment Choices

There are now more treatments than ever before for ovarian cancer. Medicine has advanced to the point at which doctors are looking at a woman’s specific tumor and figuring out a unique course of care. Specifically, they may look for a “homologous recombination deficiency,” which can indicate if the patient is a good candidate for PARP inhibitor treatments.

In the past, it was standard practice for all women with ovarian cancer to get exactly the same therapy. That’s not the case anymore, according to Rebecca Arend, gynecologic oncologist at the University of Alabama Comprehensive Cancer Center.

One way doctors have individualized treatment for ovarian cancer: they’re looking at HRD as one of the factors to consider when choosing a course of treatment for their patients.

So what is this deficiency, better known just as HRD?

It’s a genetic factor, sometimes present in women who have mutations in the BRCA gene. HRD means that a woman’s ovarian cancer cells have trouble repairing themselves. And this can make them somewhat easier to fight.

Ovarian cancer patients with homologous recombination deficiencies exhibit specific clinical behaviors, and improved responses to treatments, such as platinum-based chemotherapy and PARP inhibitors, according to researchers.

This means that women with the BRCA gene and HRD may benefit more from certain chemotherapy drugs and the cancer-attacking school of drugs known as PARP inhibitors.

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.

“BRCA mutations are the most commonly known and probably one of the first that were discovered in ovarian cancer to lead to what we call homologous recombination deficiency which is the inability to repair double strand breaks,” says Dr. Arend. “There are other genes that are in that same pathway that lead to the same problem.”

Genetic mutations in cancer are what can cause homologous recombination deficiency. They can be inherited and present in all your body’s tissues (‘germline’) or within just the cancer tissue itself (‘somatic’).

A PARP inhibitor is recommended for ovarian cancer patients with homologous recombination deficiency.

The Importance of Genetic Testing For Ovarian Cancer Patients

According to Ursula Matulonis, of the Dana-Farber Cancer Institute, it is vitally necessary for women diagnosed with ovarian cancer to be tested for BRCA not only for herself but for her family.

“These mutations are hereditary, meaning the presence of a mutation in your BRCA genes increases the risk of the mutation’s existence amongst your progeny and forebears as well,” says Matulonis. “If the BRCA1 or BRCA2 mutation is identified in your genes, the likelihood that other family members will receive ovarian cancer diagnoses later is significantly higher.”

And, testing for the mutation can help with the course of treatment, as Dr. Arend explains, treatments are becoming more personalized and knowing about mutations can help with that.

Matulonis says there are new therapies available to ovarian cancer patients with BRCA mutations and encouraging research being conducted to improve treatment outcomes.

“It’s really personalized medicine in a sense that we have all sort of been waiting for, and now it says let’s look at your tumor and depending on what mutation you have is going to depend on what therapy you get,” says Arend.

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