Ovarian Cancer Causes and Risk Factors

Ovarian cancer causes and risk factors

Ovarian cancer is a type of cancer that begins in the ovaries, the female reproductive organs that produce eggs (ova) and make female hormones (estrogen and progesterone). One ovary is located on each side of the uterus.

ovary anatomy

Types of Ovarian Tumors

There are three main types of cells in the ovaries: epithelial, germ cell, and stromal. Each cell can develop into a different type of tumor:

Epithelial tumors

These tumors start in the cells that cover the ovaries and fallopian tubes (the epithelium). This is the most common type of ovarian cancer, accounting for 85% to 90% of all malignant ovarian tumors.

Germ cell tumors

These tumors start in the cells that form eggs within the ovaries. They are rare and are most common in teens and young women.

Sex cord-stromal tumors (SCSTs)

They start in the stromal cells, which are the connective tissue cells that produce the female hormones and holds the ovaries in place. SCSTs are very rare, making up only about 1% of all ovarian cancers.

Causes and Risk Factors for Ovarian Cancer

The exact causes of ovarian cancer are unknown, but researchers believe that there are certain factors that increase a woman’s risk of developing ovarian cancer.

Some risk factors, like age and a person’s family history, can’t be controlled, while others, such as obesity and smoking, can be changed.

Increasing age

The risk of getting ovarian cancer increases with age. Ovarian cancer is often diagnosed in women over the age of 50, with the highest risk in women over 60.

Family history of certain cancers

Women who have family members with ovarian cancer have an increased risk of the disease. Also, women with a family history of cancers of the breast, uterus, colon, or rectum, may also have an increased risk of ovarian cancer.

Being overweight

Some studies have shown that being overweight or obese may increase the risk of developing ovarian cancer. A 2014 study found that women with a body mass index (BMI) above 28 seem to have a slightly higher risk of the disease. The study found that their lifetime risk increases from 2% to 2.24%. Obesity may also negatively affect the overall survival of a woman with ovarian cancer.

Use of hormone replacement therapy (HRT)

Research suggests that women who take hormone replacement therapy after menopause may have a slightly increased risk of developing ovarian cancer. Hormone replacement therapy is a treatment that is used to relieve the symptoms of menopause or other hormone imbalances.

The longer women took HRT, the greater the risk. For example, women who have taken HRT for more than 5 years have a greater risk than women who have taken it for less than 5 years. One recent study also found that how recently a woman has taken HRT affects her risk as well.


Smoking increases a woman’s risk of developing certain types of ovarian cancer. About 3% of some types of ovarian cancer seem to be linked to exposure to cigarette smoke. Stopping smoking may help to reduce your risk of ovarian cancer and many other serious health problems.

Never being pregnant or giving birth

Women who have never been pregnant have a slightly higher risk for ovarian cancer. It is possible that the higher risk in women who have never been pregnant is linked to the factors that may make it difficult for her to become pregnant.

The risk for ovarian cancer is also higher in women who have never given birth, even if they have been pregnant.

Inherited gene mutations

Women who inherit a mutation in the BRCA1 or BRCA2 gene are at higher risk of developing ovarian cancer. A mutation in BRCA1 increases the risk for ovarian cancer more than the BRCA2 mutation.

According to Summa health, the BRCA1 mutation increases risk of ovarian cancer to 45% in women by age 70, while the BRCA2 mutation increases risk of ovarian cancer to 11-17%.

Other gene mutations that can cause ovarian cancer include those associated with Lynch syndrome.

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