is hrd test a blood test?

This is now available in England, Wales, Scotland and Northern Ireland. Speak to your oncologist to see if this is an option for you.

Our DNA (a molecule in our cells that contains our genetic code and tells the cells how to work and behave) is constantly being damaged and repairing itself. This repair process is called homologous recombination. When our body is unable to repair breaks in DNA this is called homologous recombination deficiency (HRD). It means that, in those with a diagnosis of ovarian cancer and whose tumour tests positive for HRD, cancer cells have a harder time repairing themselves.

Until recently it was thought that HRD was caused mostly by BRCA1 or BRCA2 gene variants. It's now understood that HRD can include a number of genes. It's been found that around half of women with advanced high grade serous ovarian cancer have HRD.

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A sample of your tumour is needed to test for HRD. This can be taken during surgery for ovarian cancer or through a biopsy. A biopsy involves taking a small sample of body (tumour) tissue so it can be examined under a microscope.

This type of testing is called somatic testing. It only picks up variants that are present within the tumour. It doesn’t pick up if variants are present in the germline cells (changes in cells that are inherited from parents and are present in all cells of the body) too. Some people may have a variant present only in the tumour, while others may have it present both in the tumour and germline cells. So a test for a germline variant should be done separately.

If your tumour tests positive for HRD certain treatments are more likely to be effective. This includes PARP inhibitors. These are a type of targeted therapy that block the action of the PARP enzyme in cancer cells, which means they can’t repair certain types of DNA damage. Being HRD positive means cancer cells have a harder time repairing themselves. PARP inhibitors further block this repair mechanism causing more cancer cells to die.

More about targeted treatments for ovarian cancer

Last reviewed: November 2022

“This has been such a mover and shaker in the ovarian cancer world,” says Ruchi Garg, MD, Gynecologic Oncologist and National Program Director of Gynecologic Oncology at Cancer Treatment Centers of America® (CTCA). “It has been a game-changer. The side effects are fewer, in comparison to chemotherapy. Some patients may have anemia, low platelets or nausea, but the majority stabilize over time. And long-term side effects and risks such as myelodysplastic syndrome are rare.”

Cancer terms, abbreviations and acronyms often get conflated and cause confusion. To better understand why some ovarian cancer patients may be responding well to new targeted therapy treatments, here’s a glossary of some of the terms described in this article:

BRCA: Breast cancer gene. Mutations in the BRCA 1 and BRCA 2 genes may increase the risk of several cancers, especially breast and ovarian cancers.

HRR: Homologous recombination repair. HRR is a signaling pathway in cells that allow them to fix damage in the double strand of a DNA helix.

HRD: Homologous recombination deficiency. HRD occurs when HRR fails because genes are damaged or signals between receptors are interrupted.

dMMR: Mismatch repair deficiency. This occurs when cells can’t repair mistakes in DNA caused during the division process.

MSH-H: High micro-satellite instability. Microsatellites are strands of repetitive DNA that can become unstable if a cell has dMMR.

PARP: Poly (ADP-ribose) polymerase. These proteins are used to help cells repair themselves. PARP inhibitors are used to treat ovarian and other cancers.

When a car breaks down, it’s often because a part has worn out, broken or malfunctioned. If you can’t fix the part or find a replacement, the car may wind up in the scrap heap.

The same happens to some cells in our body. As a matter of course, the human body’s DNA is continually damaged and repaired. One such repair process is known as homologous recombination. Even cancer cells, which are healthy cells that have mutated and grow unchecked, get damaged and need to fix portions of their DNA in order to survive. In some cases, the cells are able to repair themselves, allowing them to continue to contribute to a cancer’s growth.

But sometimes, cancer cells have features that make it difficult to find a way to fix their broken strands of DNA, and they’re permanently shut down. Scientists are learning more about these processes in cancer cells and have developed drug therapies designed to short-circuit repair mechanisms to keep those flawed cancer cells permanently in the scrap heap.

One such repair pathway is HRR, which uses a complex set of signals between genes to fix double strands of DNA. Disruptions in those signals, or damage to the genes, may lead to HRD. Scientists have known that HRD may be found in ovarian tumors with BRCA1 and BRCA2 gene mutations, but they’re also discovering that tumors without those mutations may also have HRD.

Besides ovarian cancer, HRD may be found in other cancers, including:

PARP inhibitors, often in combination with other drugs, have been approved to treat HRD-positive ovarian cancers.

HRR and HRD are similar to dMMR and MSI-H, but work differently and fix different types of damage. When cells can’t fix mismatches in their DNA, it may cause repetitive stretches of DNA called microsattelites to become unstable. MSI-H and dMMR may be found in many cancers, including:

In 2017, the FDA approved the checkpoint inhibitor drug pembrolizumab (Keytruda®) to treat cancers with dMMR or MSI-H. It was the first cancer treatment approved based on a tumor’s genetic feature rather than its primary location

It has long been known that having a BRCA mutation—BRCA1 or BRCA2—significantly increases the risk of breast cancer in both genders, as well as ovarian, prostate and pancreatic cancers. Medical researchers are finding that women with BRCA-associated ovarian cancer are having encouraging responses to PARP inhibitors. The PARP enzyme is responsible for helping cells repair DNA damage, and in the case of cancer, helping cancer cells survive. PARP inhibitors block DNA repair in cancer cells, causing them to die. As with all targeted therapies, PARP inhibitors are designed to target the cancer cells while leaving healthy cells alone.

PARP inhibitors were first approved in 2014 to treat recurrent BRCA-associated ovarian cancer, but more recent studies have found they may also be beneficial as a first-line treatment for women who are newly diagnosed with advanced disease. Additionally, the FDA has approved PARP inhibitors for certain BRCA-associated pancreatic and prostate cancers

In one study on advanced-stage BRCA-associated ovarian cancer patients, the PARP inhibitors decreased the chance of progression or death by as much as three-and-a-half years in the upfront maintenance setting, according to Dr. Garg. “In recurrent cancers, the numbers decrease, but there’s still a significant advantage,” she says.

Until recently, doctors have focused on the presence of BRCA gene mutations to help determine treatment options for ovarian cancers. More recently, researchers have learned that HRD may occur in ovarian tumors that do not have BRCA mutations. They also have learned, Dr. Garg says, that PARP inhibitors may benefit cancer patients who are positive both for BRCA or HRD without BRCA.

This is now available in England, Wales, Scotland and Northern Ireland. Speak to your oncologist to see if this is an option for you.

Our DNA (a molecule in our cells that contains our genetic code and tells the cells how to work and behave) is constantly being damaged and repairing itself. This repair process is called homologous recombination. When our body is unable to repair breaks in DNA this is called homologous recombination deficiency (HRD). It means that, in those with a diagnosis of ovarian cancer and whose tumour tests positive for HRD, cancer cells have a harder time repairing themselves.

Until recently it was thought that HRD was caused mostly by BRCA1 or BRCA2 gene variants. It's now understood that HRD can include a number of genes. It's been found that around half of women with advanced high grade serous ovarian cancer have HRD.

Order guide Download guide

A sample of your tumour is needed to test for HRD. This can be taken during surgery for ovarian cancer or through a biopsy. A biopsy involves taking a small sample of body (tumour) tissue so it can be examined under a microscope.

This type of testing is called somatic testing. It only picks up variants that are present within the tumour. It doesn’t pick up if variants are present in the germline cells (changes in cells that are inherited from parents and are present in all cells of the body) too. Some people may have a variant present only in the tumour, while others may have it present both in the tumour and germline cells. So a test for a germline variant should be done separately.

If your tumour tests positive for HRD certain treatments are more likely to be effective. This includes PARP inhibitors. These are a type of targeted therapy that block the action of the PARP enzyme in cancer cells, which means they can’t repair certain types of DNA damage. Being HRD positive means cancer cells have a harder time repairing themselves. PARP inhibitors further block this repair mechanism causing more cancer cells to die.

More about targeted treatments for ovarian cancer

This test looks at DNA from healthy cell samples, either saliva or blood, to determine if a mutation is inherited.