Ovarian cancer is uncommon. The lifetime risk of an individual with ovaries or fallopian tubes is about 1 in 80 (about 1.3%). In addition to being uncommon and generating little awareness compared to other cancer types, it’s notoriously hard to catch early. Therefore, knowing your baseline risk and being aware of symptoms is crucial.
The risk of developing any cancer isn’t an exact science. While we can use data from those who have developed ovarian cancer to predict who is most at risk of developing it in the future, we don’t know why or how many of these factors influence risk. This means that individuals with all these risk factors may never develop ovarian cancer; unfortunately, those without any risk factors still do. So, what might influence your risk?
Risk factors
You’re at a higher risk for developing ovarian cancer if you:
1. Are over the age of 50
The average ovarian cancer patient is 63 years old. However, it’s uncommon in younger individuals (<40 years of age), so the highest diagnoses are made in those between 55 and 63.
2. Are obese
Studies to date show that carrying excess weight can influence your cancer risk. Being obese (or having a body mass index > 30) increases your risk of ovarian cancer.
3. Are infertile
Having trouble getting pregnant or keeping pregnancies (infertility) also increases your risk for ovarian cancer.
4. Had children later in life
In those who have children, people who give birth after 30-35 have an increased risk for ovarian cancer.
5. Had In Vitro Fertilization (IVF)
Going through IVF increases your risk of ovarian tumours, but these are typically the “borderline” or “low malignant potential” and not invasive.
6. Take or have taken hormone replacement therapy (HRT), especially if you did for more than five years
Using HRT with estrogen (alone or in combination with progesterone) after menopause increases your risk of developing ovarian cancer. The length of time you’ve taken them also matters — those currently using HRT are at a higher risk than those who took it in the past. Taking HRT for five years or more increases your risk compared to those who have taken it for less than five years, and taking HRT for more than ten years increases the risk even in those who have had hysterectomies (removing the uterus).
7. Have endometriosis
Endometriosis increases your risk of developing clear cell and endometrioid ovarian cancers.
8. Smoke
Smoking increases the risk of the mucinous type of ovarian cancer.
9. Are sedentary
10. Carry a familial cancer syndrome or mutation in an ovarian cancer-causing gene
About a quarter of ovarian cancers originate from familial cancer syndromes. These include BRCA mutations, Lynch Syndrome, and Peutz-Jeghers Syndrome. These syndromes are mutations in several genes known to generate ovarian tumours; however, you can carry these mutations without a known familial cancer syndrome.
11. Have a family member with ovarian cancer
If your mother, sister, or daughter (immediate family) has or had ovarian cancer, your risk increases to 5%. The risk is greater if your mother has/had it than if your daughter does/did. A larger number of family members with ovarian cancer increases this risk further.
12. Had breast, uterine or colorectal cancer (or have a family history of these cancers)
Having had breast cancer increases the risk of developing ovarian cancer. This is thought to be because of the many shared risk factors between breast and ovarian tumours. The risk for ovarian cancer may be even higher for those with breast cancer and a family history of breast cancer. Having had uterine or colorectal cancer previously also increases your risk of developing ovarian cancer. Importantly, you are also at an increased risk if your family members are diagnosed with these cancers.
You might (additional research is needed) be at a higher risk for developing ovarian cancer if you:
1. Have a high number of menstrual cycles
While it’s hard to measure this, some studies suggest that starting your period earlier (younger than 11/12) or starting menopause later (older than 50-55) may increase your risk of developing ovarian cancer.
2. Are tall
One study concluded that taller people have a slightly increased risk of ovarian cancer.
3. Have diabetes
There may be an increased risk of developing ovarian cancer in those with diabetes, which may also be higher in those who use insulin to manage their diabetes.
4. Don’t eat vegetables
Seriously, research shows not eating your vegetables may increase your risk of developing ovarian cancer.
Protective Factors
You’re at a lower risk for developing ovarian cancer if you:
1. Have given birth, especially if you did before the age of 26
Carrying a pregnancy to term and giving birth lowers the risk for ovarian cancer compared to those who have never been pregnant or have not carried to term. And your risk is reduced further with each full-term pregnancy. Also, you are at a lower risk if you gave birth before age 26.
Importantly this protection does not extend to those with a strong family history of ovarian cancer or BRCA mutations.
2. Take or have taken oral contraceptive pill (the pill), especially for more than five years
Individuals taking or who have taken the pill are at a lower risk for ovarian cancer. If you’ve taken the pill for more than five years, your risk is halved compared to those who haven’t taken the pill.
3. Have or had an intrauterine device (IUD)
Having an IUD, even for a short period, has been associated with a lower risk of ovarian cancer.
4. Had a tubal ligation (tubes tied) or a salpingectomy (tubes removed)
Having your tubes tied or removing them has been found to lower your risk for ovarian cancer. Removing both fallopian tubes can also eliminate your risk for the most aggressive ovarian cancer subtype (read more about this here).
You might (additional research is needed) be at a lower risk for developing ovarian cancer if you:
1. Had a hysterectomy (removing your uterus)
While the association is not as strong as those who have undergone tubal ligation, a hysterectomy may decrease your risk of developing ovarian cancer.
2. Breastfeeding
While it’s hard to discern the impact of pregnancy from breastfeeding, some studies have suggested that breastfeeding can further lower your ovarian cancer risk.
Other factors explored include androgens (i.e., testosterone), talcum powder, aspirin, and diet. However, conclusions on these factors’ impact on ovarian cancer risk can’t be made at this time without more research.
What can you do if you have many risk factors?
While many risk factors are out of our control (yes – we don’t know how to reverse that pesky aging thing), some are. While I won’t advocate for going through pregnancy and raising a child to lessen your risk of getting ovarian cancer, little things like keeping active, eating healthy, quitting smoking, and losing weight can decrease your risk of developing all sorts of diseases and cancers. Additionally, if you’re at a higher risk than most and are menopausal, it’s worth having a conversation with your healthcare provider about avoiding hormone replacement therapy. Most critically, be aware of the common signs and symptoms of ovarian cancer including bloating/ swelling in the abdomen, feeling full quickly while eating, weight loss, pelvic discomfort/ pain, fatigue, back pain or any abnormal uterine bleeding.
For those with family history – talk to your healthcare provider to see if your family history warrants genetic testing. If you are a known carrier of a familial cancer syndrome, ask about prophylactic measures.
