high-grade serous ovarian cancer
High-grade serous ovarian cancer (HGSOC) is the most common type of ovarian cancer. About two-thirds of people diagnosed with ovarian cancer have high-grade serous ovarian cancer. It typically affects older women, with half being over 60 years of age at the time of diagnosis.
The grade of cancer describes how much cancer cells look like normal cells. High-grade cells grow quickly and look very different to normal cells under a microscope.
Symptoms
The symptoms of high-grade serous ovarian cancer are similar to other ovarian cancers and may include any of the following: bloating; eating less and feeling fuller; bowel habit changes; needing to pee more or urgently; abdominal, pelvic or back pain; and other symptoms. Symptoms that last four weeks or longer, particularly if they are unusual, frequent or worsening, should be investigated.
Diagnosis of high-grade serous ovarian cancer
High-grade serous ovarian cancer is an epithelial cancer. Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces (like the outer surface of our skin and eyes), line body cavities and hollow organs, and are the major tissue in glands.
High-grade serous ovarian cancer is thought to mostly start in the epithelial cells of the fallopian tube before spreading to the ovary or, less commonly, to the peritoneum (lining of the abdomen). Most high-grade serous ovarian cancer is diagnosed when the cancer has spread.
Investigations for high-grade serous ovarian cancer usually include a pelvic examination, CA-125 blood test and imaging like a transvaginal ultrasound or CT. If ovarian cancer is suspected, a doctor specialising in the diagnosis of disease called a pathologist, will examine a sample of the tumour (usually taken during surgery) to confirm the diagnosis.
High-grade serous peritoneal cancer
High-grade serous peritoneal cancer is considered a variant of high-grade serous ovarian cancer. The peritoneum is the internal layer of the abdomen. In some people, high-grade serous cancer develops in the peritoneum instead of the ovary. The medical treatment for both conditions is the same.
Genetic risk factors
Approximately 1 in 5 people with high-grade serous ovarian cancer carry a mutation in the breast cancer (BRCA) 1 or 2 gene. Mutations in the BRCA gene are more common if people have a family history of ovarian cancer, breast cancer, prostate cancer and pancreatic cancer.
A genetic blood test can identify whether someone carries a germline BRCA mutation. A germline BRCA mutation can be found in all the cells in the body and may be inherited. If someone has the mutation, there is a 50% chance that siblings and children also carry the mutation.
If a BRCA mutation is identified before a cancer diagnosis, prophylactic surgery to remove the fallopian tubes and ovaries can almost eliminate the risk of developing ovarian cancer.
Learn more about hereditary ovarian cancer.
It is possible (but less common) to have a normal germline BRCA gene, but for a mutation to be found specifically in the cancer cells. This is called a somatic mutation and is not inheritable. In New Zealand, tumour testing for the BRCA mutation is available in some regions. Gynae-oncologists and oncologists can give more information about this process.
People with germline or somatic BRCA mutations may benefit from a type of targeted maintenance therapy called PARP inhibitors.
Initial Treatment
In New Zealand, treatment decisions are made in a multidisciplinary meeting. Doctors present individual cases to a group of specialists which includes gynae-oncologists, oncologists, pathologists and radiologists and together they decide what treatment should be recommended.
Initial (frontline) treatment usually consists of surgery and/or chemotherapy. Chemotherapy may be administered through the veins (intravenous) or directly into the abdomen (intraperitoneal). Most people receive some form of carboplatin/paclitaxel chemotherapy. In certain circumstances some people may also be given a targeted treatment called bevacizumab which is an anti-vascular endothelial growth factor, during and after chemotherapy.
Following chemotherapy, people may also be prescribed a PARP inhibitor as a maintenance treatment. In New Zealand, the PARP inhibitor olaparib (Lynparza) is funded in newly diagnosed people following chemotherapy if they have a BRCA mutation in their germline (detectable via a blood test) and meet certain eligibility criteria.
Another PARP inhibitor called niraparib (Zejula) is funded regardless of BCRA status. People with advanced, high-grade, platinum sensitive ovarian, fallopian tube or primary peritoneal cancer will be eligible to receive treatment if they meet eligibility criteria.
You can read more about the treatments for newly diagnosed high-grade serous carcinoma in the NCCN Ovarian Cancer Guidelines. The NCCN guidelines are an American resource and some treatments may differ in New Zealand.
What happens if high-grade serous ovarian cancer comes back after treatment?
If the cancer never goes away completely and continues to grow during or right after treatment, this is called progression. If the cancer goes away after treatment but then comes back later, this is called recurrence.
If someone experiences a recurrence or progression and the cancer takes six months or longer to recur or progress after their last dose of platinum-based chemotherapy (like carboplatin), it is said to be chemotherapy-sensitive or platinum-sensitive. If it takes less than six months to recur or progress it is considered platinum resistant.
If the cancer comes back or progresses, surgery and/or chemotherapy may be an option. Possible chemotherapy treatments include platinum-based carboplatin and non platinum-based chemotherapies such as paclitaxel, gemcitabine, doxorubicin and topotecan.
In New Zealand, the PARP inhibitor, olaparib (Lynparza) and niraparib (Zejula) may be funded for maintenance in people following chemotherapy if they have a BRCA mutation in their germline and their high-grade serous ovarian cancer returns after initial treatment (if it was not provided as part of their initial treatment) if they meet eligibility criteria.
Another PARP inhibitor called Niraparib may also be funded, regardless of BRCA status. People with advanced, high-grade, platinum-sensitive ovarian, fallopian tube or primary peritoneal cancer will be eligible to receive treatment, if they meet eligibility criteria.
You can read more about the treatments for recurrent high-grade serous carcinoma in the NCCN Ovarian Cancer Guidelines. The NCCN guidelines are an American resource and some treatments may differ in New Zealand.
Unfunded treatments
Some ovarian cancer treatments available overseas in countries like Australia and the United Kingdom are not funded in New Zealand or may have additional restrictions as to their use. Some of these treatments are only used in recurrence overseas, while others are also used as part of front-line (initial) treatment.
Treatments that are unfunded or have additional restrictions to their use include anti-vascular endothelial growth factor (VEGF) agents like bevacizumab; PARP inhibitors like rucaparib (Rubraca), Folate Receptor Antibody mirvetuximab soravtansine-gynx (Elahere); and chemotherapy agents like pegylated liposomal doxorubicin hydrochloride (Caelyx), in addition to different administration techniques like hyperthermic intraperitoneal chemotherapy (HIPEC), which is performed during surgery.
Unfunded treatments can only be prescribed in the private healthcare system. Some life insurance policies and health insurance may pay a lump sum following a cancer diagnosis, to pay for unfunded treatments. Other people decide to undertake fundraising to pay for treatments.
Not everyone will benefit from an unfunded treatment but it is your right to be fully informed about your health decisions. If your doctor doesn’t mention unfunded treatments and you would like to know more, you can ask them.
Clinical trials
A clinical trial is research involving human participants. Clinical trials can offer new or different treatment options for people with ovarian cancer, and help doctors make better decisions for people in the future. Medications in a clinical trial are provided to participants at no cost. There may be unknown benefits and unique risks to participating in a clinical trial. An oncologist or gynae-oncologist can advise if there are any clinical trials which people may be eligible for.
To learn more about clinical trials visit our clinical trials information page.
Find out more information about ovarian cancer.
Note: this content has been reviewed by a gynaecological cancer specialist in New Zealand. Information is provided for general use and should not be a substitute for professional medical advice.
Last reviewed: 16 January 2024