What is Ovarian Cancer?
Ovarian cancer is a term that encompasses a broad group of cancers that can originate from cells in the ovaries, fallopian tubes or peritoneum (a thin membrane that lines the abdominal and pelvic cavities and the surface of many internal organs).
Epithelial ovarian cancer is the most common group of ovarian cancers, and if you have heard of ovarian cancer in the media or from friends and family, it is likely this is the type of cancer being discussed. It is more likely to affect older women, and the most common subtype is called high grade serous carcinoma and affects approximately 75% of women with ovarian cancer. Other less common subtypes include mucinous, endometrioid, clear cell and low grade serous. All subtypes behave and respond to treatment in differing ways.
Non-epithelial ovarian cancer is a comparatively rare group of ovarian cancers that form from different cell types within the ovary. These include germ cells and sex cord-stromal cells. These cancers in general are more likely to affect younger women.
Cancer from other sites such as the gastrointestinal tract, breast or lymphatic system can metastasise (spread) to the ovaries and peritoneum and present in a similar way to a primary ovarian cancer.
The principal way ovarian cancer can spread is through shedding of cells within the abdominal and pelvic cavity. The cells are able to attach to peritoneum and grow. Cancer cells may also spread through the lymphatic system to lymph nodes, or the blood stream to distant organs.
What is the cause of Ovarian Cancer?
The exact cause of ovarian cancer is unknown, but it is believed to result from genetic mutations within cells that causes them to grow and multiply abnormally. Various inherited and environmental factors may promote genetic mutations, or they can occur spontaneously.
Cells make new genetic material (DNA) to replicate, and also sustain genetic damage that needs to be repaired for cells to function normally. In ovarian cancer, we now know there are detectable defects in the tumour cell’s genetic machinery that is responsible for repairing DNA (a process called homologous recombination). Therefore when DNA damage occurs, it cannot be repaired properly and the cell malfunctions.
An identifiable deficiency in the process of homologous recombination is found in a half of cases of ovarian cancer. In around 15% of cases, this is due to an inherited genetic mutation (detectable within a person’s genetic makeup) in BRCA1 or BRCA2 (the most common breast and ovarian cancer hereditary risk gene mutations). Another 10% of the time a mutation within BRCA1 or BRCA2 may occur in the tumour tissue but not exist within the person’s genetic makeup. The other 25% of the time it may be related to a less common inherited mutation or other spontaneous mutation within the cell.
The realisation of this mutation has provided an avenue for therapeutic targets with PARP inhibitors (Olaparib/Lynparza, Niraparib/Zejula, Rucaparib/Rubraca), a treatment that has revolutionised ovarian cancer treatment over the last decade.
Other risk factors include:
- age
- family history
- reproductive history including early menstruation, late menopause, never having had a pregnancy
- obesity
- smoking
- endometriosis
What are the symptoms Ovarian Cancer?
Typically symptoms may be vague and non-specific:
- Gastrointestinal symptoms – bloating, reflux, indigestion, constipation, feeling full early, lose of appetite
- Abdominal or pelvic discomfort and pain
- Increasing abdominal girth
- Abnormal vaginal bleeding or discharge, menstrual irregularities
- Increased frequency or urgency of urination
- Fatigue
- Weight loss or weight gain
- Chest symptoms – shortness of breath, chest pain
Frequently Asked Questions
If you present with symptoms of ovarian cancer, an examination should be performed, followed by an imaging study (Pelvic ultrasound +/- CT abdomen and pelvis).
Ovarian cancer may be suspected on the basis of:
- imaging tests (Ultrasound, CT scan, MRI scan etc.)
- blood tests (tumour markers)
On imaging tests, findings suggestive of cancer are an ovarian mass (cyst, growth, lesion) or pelvic mass containing solid areas and increased blood supply to those areas. Other findings may be an abnormal amount of free fluid in the pelvic or abdominal cavity (ascites) or signs of nodular growths on the peritoneum or omentum. In advanced ovarian cancer, changes in the chest may be seen for example fluid accumulation around the lungs (pleural effusion) or enlarged lymph nodes around the lungs and heart.
Tumour markers are proteins released by cells that are measurable in the blood. In many cases, both non-cancerous and cancerous cells may be able to produce certain tumour markers. For example, CA-125 (Cancer antigen 125), the tumour marker most widely used in ovarian cancer, can be elevated during a normal menstrual period, or with benign conditions such as endometriosis or adenomyosis. For this reason, an elevated tumour marker does not equal a diagnosis of cancer. For ovarian cancer, tumour markers are used in conjunction with imaging interpretation of an ovarian cyst or pelvic mass to make an assessment of the risk of cancer. They are also used to assess response to cancer treatment and to evaluate for cancer recurrence after treatment.
Definite diagnosis of ovarian cancer is based on tissue pathology. This may be of the ovarian mass after surgical removal, or evaluation of a biopsy of a tumour growth, commonly from either omentum, peritoneum or lymph node. Ovarian cancer can also be diagnosed by examining cells in abdominal fluid (ascites) or fluid around the lung (pleural effusion).
In cases where the only finding on imaging is an ovarian mass, a final diagnosis of ovarian cancer including what specific type and what stage of cancer is not available until after surgery. Cases that have an intermediate or high risk of cancer based on imaging findings and tumour markers should be performed by a gynaecological oncologist.
In women who have test results suggesting an elevated risk of ovarian cancer, but no signs of significant spread outside of the ovary on imaging, the upfront treatment is surgery. Standard treatment in postmenopausal women and for women who have completed their family is removal of the uterus, cervix, fallopian tubes and ovaries, plus additional staging biopsies that may include omentum, peritoneum, lymph nodes and peritoneal washings (fluid instilled and aspirated out of the peritoneal cavity). An intraoperative “frozen section” may be performed by a pathologist to make a preliminary diagnosis and direct what should be performed at surgery. In selected cases this surgery may be appropriate to perform laparoscopically, otherwise it is performed via an open laparotomy.
Most women with ovarian cancer diagnosed at upfront surgery go on to have chemotherapy following surgery. Some women with low grade and early stage cancers may enter close surveillance. For women diagnosed with borderline ovarian tumours (pre-cancerous change), chemotherapy is of no benefit and women enter surveillance.
In women who have test results indicating probable ovarian cancer with signs of spread outside of the ovary, a biopsy may be recommended upfront. This may be obtained either by needle/core biopsy using imaging guidance, or via laparoscopy. Depending on the biopsy result, the majority of women with an advanced ovarian cancer in Australia are treated upfront with chemotherapy (neo-adjuvant chemotherapy), and reassessed for potential surgery after at least 3 cycles of chemotherapy. The goal of this surgery (cytoreductive surgery or debulking surgery) is to remove all visible cancer as well as uterus, cervix, fallopian tubes and ovaries. After surgery women aim to restart chemotherapy within 4 weeks of surgery, to complete their remaining cycles (total of 6 cycles)
Increasingly women with advanced ovarian cancer are being treated with ‘maintenance’ therapy following chemotherapy and surgery with agents such as Bevacizumab (Avastin), or Olaparib (Lynparza) to reduce their risk of recurrence or progression.
After treatment you are closely monitored with clinical visits termed ‘surveillance’. This follow up aims to diagnose and manage cancer recurrence, manage any adverse effects of treatment, provide psychosocial support, and promote living well following a cancer diagnosis and treatment.
All types of cancer have some degree of recurrence risk after successful treatment. The degree of risk of affected by many factors including the original type and stage of cancer.
Most women who experience a recurrence of gynaecological cancer experience new symptoms. For example, symptoms such as new and persistent abdominal pain, change in bowel habit, vaginal bleeding, chest pain. If you experience new symptoms contact your health care provider, either specialist or GP. A full examination will be conducted and often imaging studies (e.g. CT scan). Often a tissue biopsy will be required if there are abnormalities on examination or imaging.
Available cancer directed treatment will depend on a number of factors including the site and extent of recurrence, previous treatment history, personal medical history and your preferences.
In some cases, non-standard fertility preserving treatment may be possible based on safety evidence. This may include preservation of uterus and one ovary. Preservation of oocytes/eggs is possible in some cases.
Ovarian cancer cannot be prevented, but there are several factors associated with a reduced risk of ovarian cancer:
- Prophylactic surgical removal of the fallopian tubes and ovaries
- Prophylactic surgical removal of fallopian tubes
- Oral contraceptive pill
- Permanent surgical contraception (tubal ligation in the past, however current recommendation is for bilateral salpingectomy i.e. removal of both fallopian tubes for contraception and maximal ovarian cancer risk reduction)
- Maintain healthy body weight
- Healthy well balanced diet
- Avoid smoking
- Regular exercise
Screening
Despite scientific investigation, we do not have a proven screening strategy or screening test for ovarian cancer that diagnoses the disease early enough to save lives. In the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) study [reference], that involved over 200,000 women followed up until December 2024, despite more cases of ovarian cancer being diagnosed at an earlier stage, yearly screening with ultrasound and CA-125 did not improve overall mortality.
Reference: Menon U, Gentry-Maharaj A, Burnell M, Singh N, Ryan A, Karpinskyj C, Carlino G, Taylor J, Massingham SK, Raikou M, Kalsi JK, Woolas R, Manchanda R, Arora R, Casey L, Dawnay A, Dobbs S, Leeson S, Mould T, Seif MW, Sharma A, Williamson K, Liu Y, Fallowfield L, McGuire AJ, Campbell S, Skates SJ, Jacobs IJ, Parmar M. Ovarian cancer population screening and mortality after long-term follow-up in the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS): a randomised controlled trial. Lancet. 2021 Jun 5;397(10290):2182-2193. doi: 10.1016/S0140-6736(21)00731-5. Epub 2021 May 12. PMID: 33991479; PMCID: PMC8192829.
Getting to know what is normal for your body is important. Only if you are familiar with normal can you recognise anything new and potentially abnormal. Any new symptoms as outlined above should be reported to your GP and investigated.
If you are facing a new diagnosis of ovarian cancer or suspected ovarian cancer, write down any questions you can think of, bring a family member or friend to your specialist appointment, and reach out to those around you and the resources below for support.