Whether you’re newly diagnosed with ovarian cancer or have been living with it for some time, one of the most important steps you can take is understanding the specifics of your disease. Ovarian cancer is not just one condition, and knowing your exact type can directly impact your treatment options.
We asked UCLA Health’s Dr. Beth Karlan to explain the different types of ovarian cancer and why germline and genomic testing are a critical part of your care.
Ovarian cancer is not one-size-fits-all
In the past, ovarian cancer was often treated as a single disease. Over the last decade, research has shown that there are several distinct types that behave differently.
Most ovarian cancers are called epithelial ovarian cancers. Within this group, there are five main types:
- High-grade serous (the most common, about 75% of cases)
- Low-grade serous
- Clear cell
- Endometrioid
- Mucinous
There are also less common ovarian cancers, including germ cell tumors and stromal tumors, which have their own risk factors and treatment approaches.
“These distinct subtypes look different under the microscope,” Dr. Karlan says. That microscopic appearance, known as histology, is one of the first clues that helps guide treatment.
Why does this matter? Dr. Karlan shares that different subtypes can respond differently to standard chemotherapy and these differences are especially important if cancer returns. “When you get into the recurrence setting, it’s even more important because many of the new treatment advances are [based on] understanding those molecular drivers,” she notes.
Three key questions to ask your doctor
Dr. Karlan emphasizes that every patient should understand:
- What type of ovarian cancer do I have?
- What stage is it?
- Are there specific molecular or genetic characteristics that could guide treatment either now or in the future?
These details play a significant role in helping your care team personalize your treatment plan.
The role of genetics in ovarian cancer
Genetics is another key factor in guiding your care. “All ovarian cancers are genetic diseases,” Dr. Karlan explains. This doesn’t necessarily mean they are inherited, but it does mean they develop because of changes (mutations) in genes inside cells.
There are two main types of genetic testing that may be recommended: germline testing and tumor testing.
Germline genetic testing (Assessing inherited risk)
Some people inherit a predisposition to ovarian cancer through genes passed down in their family. You may already be familiar with the BRCA1 and BRCA2 genes, but several genes can increase ovarian cancer risk.
“It’s very important, whether you’re just diagnosed or you’re a survivor at a later time, that you have this germline genetic testing done,” Dr. Karlan says. This simple test can be done using blood or saliva because it looks for genetic changes that are present in every cell of your body.
Why is this important?
- It may help guide treatment decisions.
- It can identify whether targeted therapies like PARP inhibitors may benefit you.
- It provides important information for family members who may also be at risk.
Tumor/genomic testing (Molecular profiling)
In addition to inherited genes, cancer cells can acquire genetic alterations over time. Dr. Karlan notes that these changes can evolve as the cancer grows or after treatments like chemotherapy.
For tumor testing, doctors analyze the DNA inside the tumor itself to look for specific mutations. This process, called sequencing, helps answer a crucial question: Are any of these mutations targetable with today’s treatments?
Dr. Karlan explains that tumor testing is often done at diagnosis and may be repeated at recurrence, because “the molecular profiling can change.”
This information can help determine:
- Maintenance treatment options
- Targeted therapies
- Future treatment strategies
What is HRD and why does it matter?
One important tumor characteristic is called homologous recombination deficiency (HRD).
HRD is found in nearly 50% of epithelial ovarian cancers, especially in high-grade serous cancers. Patients whose tumors have HRD — as well as those with BRCA mutations — often benefit from PARP inhibitors, a type of targeted treatment, used as maintenance therapy.
Personalizing ovarian cancer treatment
“As we look to individualize treatments,” Dr. Karlan says, the goal is to sequence therapies in a way that provides “the most benefit and the most time to be off treatment.” By using detailed information about your cancer’s type and genetics, your care team can choose the most effective therapies, help reduce side effects, and plan smarter treatment strategies over time.
If you or a loved one has ovarian cancer, don’t hesitate to ask questions about your diagnosis and test results. The more you understand about your specific cancer, the more empowered you’ll be to partner with your care team and make informed decisions about your treatment.
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