Causes of Ovarian Cancer

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The precise cause of ovarian cancer is unknown, but several risk factors have been associated with developing the disease. Having a risk factor increases the risk of developing the cancer, but does not definitively mean that you will get it. Similarly, having no risk factors does not mean that you definitely will not develop cancer

A small percentage of ovarian cancers (about 10%) have a hereditary component, in other words, several cases occur in the same family. Sometimes the altered genes in these families are already known, such as BRCA mutations (which also predispose to breast cancer) or those that form part of Lynch syndrome

Risk factors of Ovarian Cancer

There are risk factors for developing the disease, as well as protective factors. However, often none of these factors are identified in women who have ovarian cancer. Some factors can be modified medically, through preventive surgery or by taking contraceptives, but others cannot, such as age.  

Factors that increase the risk

Family and family tree indicating hereditary factors

Family history. A clear family history of breast or ovarian cancer increases the risk. 

DNA molecule or helix

Genetics. Between 10%-15% of ovarian cancers are caused by a mutation in a known gene that has been passed down within a family, such as the BRCA1 or BRCA2 gene mutation. While a woman normally has a 1%-2% risk of developing cancer, a woman with a BRCA1 or BRCA2 mutation has a risk of about 40% and 10-20%, respectively. There are many other known mutations, although these are rare, such as Lynch syndrome, among others. 

Woman growing older from childhood to old age

Age. 50% of women with ovarian cancer are aged over 60. Even so, some specific rare types affect younger people, including girls, such as germ cell tumours.

Obesity can be cause and/or risk factor of Rheumatoid Arthritis

Obesity. Obese women are more at risk. 

Female reproductive system

Endometriosis. Whether endometriosis is a risk factor is still being studied. It may increase the risk of clear cell epithelial and endometrioid cancers. 

People of different skin tones

Ethnic origin. Women from North America, Northern Europe and those with Ashkenazi Jewish heritage have a higher risk. 

Woman who cannot get pregnant

Reproductive history. Women who have not had children, who are infertile (unable to have children) for no apparent reason, or who have not taken birth control pills may have an increased risk. Fertility drugs have also been associated with an increased risk of contracting ovarian cancer, but this has not been shown to be the case. 

Hormone therapy pills

Hormone replacement therapy. Oestrogen-only hormone replacement therapy after menopause increases the risk of cancer over time. The risk decreases progressively after the treatment ends. 

Factors that decrease risk (prevention)

Oral contraceptives

Taking birth control pills. These may reduce the risk of developing ovarian cancer by 30-50%. In addition, this reduced risk can last for up to 30 years after you stop taking them. 

Breast and baby suckling

Breastfeeding. The protection increases with the cumulative time spent breastfeeding. 

Pregnant woman

Pregnancy. The more full-term pregnancies a woman has had, the lower her risk. 

Radical hysterectomy

Surgical procedures. Women who have had a hysterectomy (partial or total removal of the uterus), a tubal ligation, or a salpingectomy (removal of the fallopian tubes) have a lower risk. Early preventive bilateral salpingo-oophorectomy (removal of fallopian tubes and ovaries) is recommended for women who have been mothers and who are at very high risk of ovarian cancer (BRCA mutations or Lynch syndrome). It is also recommended for patients over 60 years of age who are undergoing pelvic surgery. Salpingectomy may be recommended in young patients who do not wish to become mothers, while undergoing pelvic surgery (hysterectomy, ovarian cystectomy, appendectomy, etc.). Women considering preventive ovarian surgery should discuss the consequences of ovary removal (which involves the cessation of hormonal function, in other words menopause) with their medical team, including the expected preventive benefits.  

Substantiated information by:

Lydia Gaba

Published: 3 July 2020
Updated: 3 July 2020

The donations that can be done through this webpage are exclusively for the benefit of Hospital Clínic of Barcelona through Fundació Clínic per a la Recerca Biomèdica and not for BBVA Foundation, entity that collaborates with the project of PortalClínic.


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