The ovaries are female reproductive glands responsible for producing and releasing eggs. They are also the primary locus for progesterone and estrogen production. They are located on either side of the uterus, and attach to it via the fallopian tubes.
Ovarian cancer mainly develops in older women, with about half of diagnoses after the age of 63. It is rare before the age of 40. Ovarian cancer is more likely to cause symptoms once it has spread, but even early stage cancer can commonly cause:
Pelvic or abdominal pain
Bloating
Fatigue
Feeling full quickly / after eating little
Back pain
Increased urinary urgency and/or frequency
Pain during sex
Upset stomach
Constipation
Menstrual cycle changes / irregular menstrual bleeding / heavier than normal periods
Abdominal swelling coinciding with weight loss
These symptoms may be caused by any number of health conditions, but when they are a change from your normal experience, increase in severity, or are persistent, they may indicate ovarian cancer. Unexplained symptoms should always be evaluated by a medical professional.[1]
The ovaries are made up of three types of cells: epithelial cells which cover the outer surface, germ cells which eventually mature into eggs, and stromal cells which form the ovaries’ connective tissues. Different forms of ovarian cancer form in each of these cells, and are characterized by distinct features and biological behaviors:
Epithelial carcinoma: These cancers begin on the surface of the ovaries and make up 85-90% of all ovarian cancers. Epithelial carcinomas can be further subcategorized based on the nature of the tumor cells and how fast they appear to be growing.
Primary peritoneal carcinoma (PPC): This rare form of ovarian cancer is very similar to epithelial carcinoma, but it appears to form in the cells lining the interior of the fallopian tubes. Treatment and prognosis is likely to be the same as with epithelial carcinoma.
Fallopian tube cancer: Like PPC, this rare form of ovarian cancer originates in the fallopian tubes and is likely to follow a treatment plan similar to epithelial carcinoma. The prognosis, however, is slightly better.
Germ cell tumors: Less than 2% of ovarian cancers are germ cell tumors, which can be further divided by subtype. Overall, they have a good prognosis.
Stromal cell tumors: Just 1% of ovarian cancers are stromal cell tumors, and while most occur in older women, around 5% of these cancers are found in young girls. The most common symptom is abnormal vaginal bleeding. These cancers are more likely to be found early.
There are also both benign and precancerous growths that can form in the ovaries, such as ovarian cysts. Depending on the type of growth and its severity, these may or may not require further treatment.
Ovarian cancer survival rates are based on how far the cancer has spread:
Localized: There is no sign the cancer has spread outside the ovaries.
Regional: The cancer has spread to nearby structures or lymph nodes
Distant: The cancer has spread to distant parts of the body, such as the liver or lungs.
The 5-year survival rate for each stage is shown below:
Incidence
Below is the overall incidence of ovarian cancer by age group:
Risk Factors
There are several confirmed risk factors that contribute to an individual’s risk for ovarian cancer:
Smoking & secondhand smoke exposure: Smoking and secondhand smoke increase your risk of many cancers, and increase your risk for the mucinous type of ovarian cancer. Tobacco smoke contains numerous carcinogens that can lead to genetic mutations and uncontrolled cell growth, ultimately resulting in cancer. Quitting smoking at any age can significantly reduce the risk of cancer and other smoking-related diseases. The body begins to repair itself almost immediately after quitting, with the risk of cancer decreasing over time. Even individuals who have smoked for many years can benefit from quitting, as the risk decreases with each year of abstinence.
Late first pregnancy / never carrying a pregnancy to term: Having your first child after the age of 35, or never having children, correlates with a higher overall risk of ovarian cancer.
Alcohol use: Alcohol has been shown to increase the risk of ovarian cancer. This risk increases the more you drink.
Post-menopausal hormone therapy: Estrogen therapy post-menopause, whether on its own or combined with progesterone, has been shown to increase the risk of ovarian cancer.
Health conditions: some text
Endometriosis[2]: Endometriosis–a condition where endometrial tissue grows outside the uterus–increases the risk of ovarian cancer more than four-fold. Depending on the location and severity of the endometrial growths, this risk may grow to nearly 10 times the risk of a woman without endometriosis.
Pelvic inflammatory disease (PID)[3]: A meta-analysis of 16 studies has shown that PID significantly increases the risk of ovarian cancer.
Genetic conditions: As many as 25% of ovarian cancers are caused by inherited genetic conditions. Conditions that increase one’s risk include: some text
Hereditary breast and ovarian cancer syndrome (HBOC, caused by mutations to the BRCA1 or BRCA2 gene)
MUTYH-associated polyposis
Peutz-Jeghers syndrome
Family history of ovarian, breast, or colorectal cancers: A family history of any of these cancers, even without a known hereditary cancer syndrome, increases one’s risk of developing ovarian cancer.
Breast cancer: A previous breast cancer diagnosis may raise your risk of also developing ovarian cancer. This risk is highest in women who also have a family history of either breast or ovarian cancer.
Blood types A and AB: Compared to other blood types, individuals with blood types A or AB have an increased risk of ovarian cancer.
Height: Research has consistently shown a correlation between height and an increased risk of several types of cancer, including ovarian. Taller individuals tend to have higher levels of IGF-1, a hormone that plays a critical role in growth and development. IGF-1 can promote cell proliferation and inhibit cell death, which may contribute to the development and progression of cancer. Taller individuals also have more cells in their body simply due to their size, which leads to a higher probability of cells mutating.
Asbestos exposure[4]: A meta-analysis of post-2012 studies on asbestos has found asbestos exposure more than doubles the risk of developing ovarian cancer. The same analysis showed that asbestos exposure corresponds with poorer outcomes.
Protective Measures
Several factors have been shown to have protective effects against ovarian cancer:
Maintaining a healthy weight: Numerous studies have linked higher BMI to increased risk of various types of cancer, including ovarian. Excess body fat can lead to higher levels of estrogen and insulin, as well as increased production of insulin-like growth factors. Higher BMI is also associated with chronic low-level inflammation, which can cause DNA damage over time and contribute to the development of cancer. Maintaining a healthy weight may also improve your prognosis if you are diagnosed with ovarian cancer.
Physical activity: Regular exercise can reduce your risk of several types of cancer through a combination of physiological, hormonal, and immunological changes. It can reduce inflammation, improve immune function, improve hormonal regulation, and lower insulin levels. The American Cancer Society recommends engaging in at least 150 minutes of moderate activity or 75 minutes of vigorous activity each week. Furthermore, data indicates that individuals can see significant incremental benefit with additional exercise.
Fruit and vegetables: Fruit and vegetables are rich in various nutrients which have been shown to have protective effects against multiple cancers, including ovarian. These foods contain a variety of antioxidants, which help neutralize free radicals in the body and reduce inflammation.
Oily fish: Oily fish (such as salmon, mackerel, trout, sardines, and herring) are known to have various health benefits. Rich in omega-3 fatty acids, protein, vitamins, and minerals, studies have shown that eating oily fish has protective effects against several types of cancer, including ovarian, and that increased consumption increases these benefits.
Breastfeeding: Women who breastfeed their children have a lower risk of ovarian cancer. There is a greater reduction in risk the longer one breastfeeds.
Early first pregnancy: Women who have carried a child to term before the age of 26 have a lower overall risk of ovarian cancer.
Contraceptive pills / IUD / tubal ligation: Both hormonal and intrauterine birth control has been shown to decrease the risk of ovarian cancer, and the benefits extend years beyond cessation of the birth control method. A tubal ligation, another method of birth control which permanently blocks the fallopian tubes, has also been shown to reduce risk.
Aspirin[5]: A daily aspirin regimen has been shown to reduce the risk of ovarian cancer.
Oophorectomy: Surgery to remove the ovaries as well as the fallopian tubes has been shown to reduce the risk of ovarian cancer by as much as 98%[6], though this intervention is usually only recommended for those at high risk for the disease.
Screening
Early detection of ovarian cancer has a dramatic impact on prognosis. The 5-year survival rate for localized cancer is around 91.9%, but drops to just 31.4% once the cancer has spread to distant parts of the body.
Depending on your age and risk factors, the optimal ovarian cancer screening will vary:
Regular pelvic exams: Though ovarian cancers are often difficult to detect at an early stage and are not usually found via Pap smears, regular pelvic exams can help detect other problems, and any possible symptoms you might be experiencing are likely to be recognized by an OB-GYN, who could recommend further testing.
Transvaginal ultrasound (TVUS): This form of ultrasound is conducted via a wand that is inserted into the vagina. It can detect any masses on the ovaries, though it will not be able to show whether they’re malignant (most masses found via TVUS turn out to be benign).
CA-125 test: This blood test specifically looks for CA-125, a substance released by many ovarian and endometrial cancers (though not all; a negative result is not a guarantee these cancers are not present). Elevated levels may alternately indicate endometriosis or pelvic inflammatory disease. Levels can also indicate whether a diagnosed cancer has progressed.
CT scan: While not routinely used as a screening tool–CT scans can miss smaller ovarian tumors–a regional CT scan can help identify larger ovarian cancers, and show whether they have spread.
Blood and tumor marker tests: Blood tests can check levels of certain substances that, when elevated, may indicate tumors associated with different forms of ovarian cancer: human chorionic gonadotropin (HCG), alpha-fetoprotein (AFP), lactate dehydrogenase (LDH), and inhibin.
Genetic testing: Genetic testing focused on the mutations known to cause ovarian cancer can help give you a better idea of your overall risk, and may affect your treatment plan if ovarian cancer is discovered. Genetic testing is particularly useful for individuals with a family history of ovarian cancer. It should be noted that while many common at-home genetic testing services claim to test for BRCA1 and BRCA2 mutations, they only test for a small selection of the over 1000 mutations on these genes that can predispose someone to cancer, and do not test for the most common mutations of these genes. To truly know your risk, these tests should be performed by a doctor.
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