OVARIAN CANCER CAUSES AND RISK FACTORS
Learn about ovarian cancer, including risk factors, diagnosis, treatment, stories from our community, and where to find support.
OVARIAN CANCER CAUSES
Ovarian cancer symptoms are often vague and are commonly attributed to other health complaints such as menstruation, menopause, or gastrointestinal issues. Currently, there is no reliable early detection test for ovarian cancer — that’s right, cervical cancer screening does not detect ovarian cancer — so it’s important to understand your individual level of ovarian cancer risk based on your age, cultural background, lifestyle, other health conditions, and more.
Ovarian cancer risk, and decisions made to reduce risk, shouldn’t be made in isolation but rather in consideration of an individual’s unique medical context. Below is a list of the known associated risks with ovarian cancer. This overview may help inform your discussion with your trusted medical professional.
Last updated
1 February 2025
A note on language
Although the term “woman” is used throughout, and ovarian cancer is primarily diagnosed in people identifying as women or girls, it is important to include and acknowledge that ovarian cancer can affect any person with ovaries, including but not limited to transgender men, intersex, non-binary and gender-diverse individuals.
AVERAGE OVARIAN CANCER RISK
In 2023 the average lifetime risk of being diagnosed with ovarian cancer by the age of 85 was 1 in 87 [i] but certain factors can increase this risk for some individuals.
While some cases can be linked to genetic changes called ‘variants’, the cause of most cases remains unknown and research into ovarian cancer risk factors is ongoing. The good news is that recent research has offered important insights, as discussed below.
OVARIAN CANCER RISK FACTORS
Who is at risk of ovarian cancer?
The below factors have been associated with an increased risk of ovarian cancer diagnosis:
- Tobacco smoking[ii]
- Age: The risk of ovarian cancer has generally been considered to increase with age and in 2010 an extensive review by the Australian Institute of Health and Welfare (AIHW) showed that many diagnoses (approximately 60%[iii]) occur in women over 60 yrs[iv]. However, 2020 AIHW [v] data showed that over a third of ovarian cancer cases in Australia are occurring in women under 60, meaning it can impact across age groups.
- A family history of ovarian, breast or colon cancer[vi]
- Genetic predisposition: such as inherited BRCA genetic variants (see below)
- Individuals from particular ethnic backgrounds including Ashkenazi Jewish descent[vii]
- Medical conditions and considerations including endometriosis (see below), Lynch Syndrome[viii], Peutz-Jeghers syndrome[ix], obesity, and diabetes[x]
- Hormonal levels can influence the risk of various types of cancer, including ovarian, in different ways[xi].
Understanding ovarian cancer risk factors
It’s important to remember that while an endometriosis diagnosis can increase ovarian cancer risk, the overall relative risk of developing ovarian cancer is low and research on this association is ongoing.
In 2024, a research study[xii] indicated that endometriosis was associated with a 4-fold increased risk of epithelial ovarian cancer, with some endometriosis subtypes correlating with even higher risk. Australian researchers[xiii] have also associated endometriosis with an increased risk of developing some rare ovarian cancer subtypes including endometroid ovarian cancer and other subtypes that can be difficult to treat with chemotherapy.
Hormonal levels can influence the risk of various types of cancer in different ways[xiv].
Higher oestrogen levels have been associated with increased ovarian cancer risk, while progesterone use, and combined oestrogen/progesterone use is associated with reduced ovarian cancer risk. Some research indicates that oral contraceptive use, pregnancy and breast feeding can reduce risk. Risk may be reduced by up to 50%[xv] in the case of combined oral contraceptives[xvi] that include some progesterone and, recent research indicates a similar risk reduction associated with longer acting hormonal contraceptives[xvii] such as IUDs. In 2024, researchers from the United States published a study indicating that estrogen-only HRT therapy could increase the risk of ovarian cancer incidence[xviii]. Although further research is required, Australian researchers indicated in 2024 that using menopausal hormone therapy, regardless of age, was not associated with poorer survival of ovarian cancer and, in some cases, menopausal hormone therapy was associated with improved survival of high-grade serous ovarian cancer.
Although estrogen use appears to be associated with an increased risk, while progesterone use is associated with a decreased risk of ovarian cancer, progesterone use has also correlated with an increased risk for some other cancers[xix]. Additionally, hormonal therapies can have significant side effects. Therefore, consultation with your doctor is important to inform medical decisions concerning hormones to ensure your individual risk of ovarian cancer is considered alongside any risk of other cancers or conditions.
Talcum powder use in the genital area is associated with an increased risk of ovarian cancer[xx], with one study associating a 33%[xxi] increased risk.
Genetic ovarian cancer risk factors
Some inherited harmful changes or ‘variants’ in genes have been linked to an increased risk of ovarian cancer and genetics is associated with approximately one fifth[xxii] of ovarian cancer cases.
Epithelial ovarian cancer, the most common kind of ovarian cancer, includes subtypes[xxiii] such as high and low grade serous, endometrioid, clear cell and mucinous. According to the National Comprehensive Cancer Network in the United States, key genetic variants understood to increase risk of epithelial ovarian cancer include[xxiv]:
BRCA1 and BRCA2 are genes involved in the DNA repair. An estimated 39%-58% of women with a BRCA1 variant are likely to develop ovarian cancer. For BRCA2, this rate sits at 13%-29%. These rates are also consistent with those reported recently by Inherited Cancers Australia where more information is available.
Some research[xxv] has indicated that a portion of prostate cancer cases are associated with inherited BRCA1 and BRCA2 genetic variants, and therefore family members, including men and fathers, could also pass on genes that increase ovarian cancer risk.
10-20% of women with this genetic variant are likely to develop epithelial ovarian cancer, as evidenced in research published in 2020 analysing data from over 6000 families[xxvi].
10%-15% of women with a RAD51C variant are likely to develop ovarian cancer according to the United States National Comprehensive Cancer Network. However, Wellcome Sanger Institute researchers published findings in 2024 that identified 3000 potentially harmful genetic changes associated with RAD51C[xxvii], which suggest carriers of the RAD51C variant could have a more than 8 times increased risk of developing epithelial ovarian cancer than those without.
Between 5%-15% of BRIP1 carriers have a likelihood of developing ovarian cancer by age 80[xxviii].
There remains a need for research to further examine genetic risk associations with rarer forms of ovarian cancer including borderline ovarian tumours, germ cell tumours, and sex cord stromal tumours such as granulosa cell tumours.
Although the cause of germ cell tumours is unknown, researchers at the Memorial Sloan Kettering Cancer Center indicate that sometimes these tumours appear in children who have genetic syndromes such as Klinefelter syndrome.
OCRF-funded research led by Associate Professor Simon Chu [CL1] is investigating the potential role of genetic variant FOXL2 in the development of granulosa cell tumours. Additionally, researchers from the MD Cancer Center have indicated that KRAS genetic mutations are associated different cancers.
Ethnicity and increased risk of ovarian cancer
Ashkenazi Jewish individuals have a higher risk of ovarian cancer diagnosis, and further research is needed to identify other populations who could also have a higher genetic risk. In the general population, the risk of carrying a BRCA mutation is 1 in 400. Although risk can vary depending on ancestry, Ashkenazi Jewish individuals have a 1 in 40 chance of carrying a BRCA mutation[xxix], and therefore an increased risk of ovarian cancer.
Research by Associate Professor Sophia George from the Miller School of Medicine, USA, has highlighted specific challenges for some Black women. Her research looks at how common BRCA variants are in people from diverse ethnicities to identify other BRCA genetic variants that may not be detected through currently available genetic tests. Additionally, research[xxx] has indicated that women of non-European ethnicity can have a higher association with ‘variants of uncertain significance’ — which means researchers identified genetic changes but whether they increase cancer risk remains unknown and required further research. This is an important area of research towards achieving equity in cancer outcomes, including in Australia where First Nations People were identified to have a 14%[xxxi] higher incidence of all cancers (between 2012-2016). However, in conducting this future research, it will be important to ensure that data sovereignty is prioritised with data collected, stored and published ethically and with consent from First Nations People.
Ovarian cancer risk-related questions
Deciding on what, if any, action to take in relation to your individual ovarian cancer risk can be difficult and should be done in consultation with your doctor. However, finding and navigating useful resources to take when you see your doctor, to prompt these conversations, can also be difficult. Therefore, the details below aim to provide additional context to some of key considerations including genetic testing and risk-reduction surgery.
Speaking with family members is a great way to identify any family history of ovarian cancer, or other cancers or conditions associated with ovarian cancer, which in turn helps your doctor understand your familial risk.
An Australian online tool, iPrevent, assesses breast cancer risk, which can be associated with ovarian cancer risk. Designed by researchers from the Peter MacCallum Cancer Centre, iPrevent provides a tailored risk report that can be discussed with a trusted medical professional. Additionally, personal information isn’t saved once the assessment session ends. Although not ovarian cancer-specific, iPrevent points to some of the ovarian cancer risk-related questions to help guide your discussion with a medical professional.
One of the two algorithms that underpins iPrevent is also used in a United Kingdom online tool for medical professionals, CanRisk, which assesses both breast and epithelial ovarian cancer risk. The Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA) is a risk prediction model, which considers the genetic mutations, including those discussed above, linked to ovarian cancer. A 2024 study[xxxii] found the BOADICEA algorithm could predict 10-year ovarian cancer risk with 78% accuracy, suggesting suitability for use by medical professionals.
In Australia genetic testing is generally available for anyone via a Familial Cancer Centre however, if ineligible for Medicare funding, it can cost approximately $450. Parkville’s Familial Cancer Centre referral guidelines note that referral is usually recommended for individuals where their family are carriers of genetic variants that increase their risk of cancer (such as those mentioned above), or there is a family history of breast or ovarian cancer.
Medicare funding for testing is generally only applicable to those who have a breast or ovarian cancer diagnosis and are assessed as having a likelihood of genetic mutation greater than 1 in 10. A doctor can help make this assessment and referral, though the Peter MacCallum Cancer Centre indicate that those with most types of ovarian cancer are eligible.
Genetic risk assessment can be important for those diagnosed with ovarian cancer because it can help doctors confirm the most effective treatment strategy for them. For example, those with BRCA variants have a dysfunctional DNA repair system called homologous recombination deficiency (HRD) which means they are likely to be eligible and respond well to a type of treatment called PARP inhibitors.
Previously there has been little protection for people with a genetic risk of cancer and their ability to claim life insurance and Monash University public health researcher Dr Jane Tiller has published research evidencing the need for legal reform due to discrimination by some Australian insurers. This advocacy is prompting reform which the government announced in September 2024. While the government’s announcement banning discrimination based on genetic tests is good news, the ban itself is yet to be enacted. In the meantime, the University of New South Wales previously documented some key legal considerations.
Reducing risk can involve some big decisions. Although ovarian cancer can be more effectively treated when diagnosed early, most cases are diagnosed in later stages due to the lack of an early detection test. For this reason, those at high-risk may discuss risk reduction measures, which are predominantly surgical and may have side effects. Whether or not to have risk-reducing surgery is a complex and personal decision and it is important to consider risk factors applicable to your unique medical context in consultation with your doctor.
Cancer Australia and the Royal Australian College of General Practitioners consider currently available screening approaches as ineffective in monitoring those at a high risk of ovarian cancer who do not have symptoms.
There’s evidence [xxxiii] that most ovarian cancers start in the fallopian tubes rather than the ovary. Although other surgeries may be recommended for treatment of ovarian cancer, risk-reduction surgery prior to an ovarian cancer diagnosis generally refers to a:
- salpingectomy (removal of one or both fallopian tubes),
- partial salpingectomy (removal of part of the fallopian tube),
- bilateral salpingectomy (removal of both fallopian tubes), or
- bilateral salpingo-oophorectomy (removal of fallopian tubes and ovaries). This is currently considered by Cancer Australia as an effective risk-reducing strategy for those at high risk.
‘Opportunistic salpingectomy’ generally occurs when a person is having abdominal surgery for another reason, and they elect to have their fallopian tubes additionally removed to reduce their risk of ovarian cancer. The International Journal of Gynaecology and Obstetrics released a statement discussing data that indicates that salpingectomy among the general population can decrease ovarian cancer risk by 42%-77%[xxxiv]. This is a large portion of ovarian cancers are now thought to originate in the fallopian tubes.
The Royal Women’s Hospital provides details side effects and management strategies for those considering risk-reducing surgery. Some side effects of risk-reducing removal of fallopian tubes and ovaries can include early menopause and longer-term risk of conditions including osteoporosisiv and dementiav. Some studies have shown that removing the fallopian tubes first, then ovaries later can minimise side effects and enable a better quality of life[xxxvii]. Additionally, removal of one fallopian tube while preserving the other can allow for pregnancy. TUBA WISP II is an Australian research trial underway through The University of Queensland to determine whether removal of both fallopian tubes with delayed removal of ovaries is just as effective at reducing risk over time and facilitates a higher quality of life.
Understanding your risk of ovarian cancer is important. It’s also important to remember that on average the risk of developing ovarian cancer remains low.
The above risk factors and risk-reduction strategies, if applicable, should be considered with an individual’s broader medical profile in mind, and in consultation with a medical professional.
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