A risk factor is anything that may increase your chance of having a disease. Risk factors for a certain type of cancer might include smoking, diet, family history, or many other things. The exact cause of someone's cancer may not be known. But risk factors can make it more likely for a person to have cancer.

Things you should know about risk factors for cancer:

• Risk factors can increase a person's risk, but they don't always cause the disease.
• Some people with one or more risk factors may never develop cancer. Other people have cancer and no known risk factors.
• Some risk factors are very well known. But there's ongoing research about risk factors for many types of cancer.

Some risk factors, such as family history, may not be in your control. But others may be things you can change. Knowing the risk factors can help you make choices that might help lower your risk. For instance, you may choose to eat healthy foods if an unhealthy diet is a risk factor. Your doctor may help you lose weight if extra weight is a risk factor.

These are the risk factors for ovarian cancer:

A person's risk for ovarian cancer rises with age. Most of these cancers happen after menopause.

Obesity means being very overweight. This increases the risk for ovarian cancer and many other cancers. It also increases the risk of dying from it.

People who have never given birth or who had their first pregnancy after age 35 have a higher risk of ovarian cancer.

People who have used estrogen replacement therapy after menopause have a higher risk for ovarian cancer. The risk increases the longer estrogen replacement therapy is used.

A mother or sister is a first-degree relative. You have a higher risk if you have two or more first-degree relatives who've had ovarian cancer. This means gene changes (mutations) passed on in families may be a cause. A family history of breast, endometrial, pancreatic, prostate, or colon cancer may also mean your family could have certain gene mutations that increase the risk for ovarian cancer.

Syndromes passed in families and linked to increased risk of ovarian cancer include:

• Lynch syndrome or hereditary nonpolyposis colon cancer. This increases a person's risk of having ovarian, uterine, colon, and other cancers at a much younger age than normal.
• Peutz-Jeghers syndrome. This rare genetic syndrome is caused by a certain gene mutation (gene STK11). It's linked with a higher risk for ovarian, breast, uterine, esophagus, stomach, colon, and lung cancer.
• MUTYH-associated polyposis. This causes polyps in the colon and small intestine. It's linked with a high risk for colon cancer. It also puts people at a higher risk for other cancers, including ovary and bladder cancers.

A personal history of breast, uterine, rectal, or colon cancer puts you at a higher risk for ovarian cancer.

If you've used fertility medicines, you may be at increased risk for ovarian cancer. But not all studies agree on this.

Endometriosis is when the inside lining of the uterus (endometrium) grows in abnormal places in the abdomen. It may increase the risk for certain types of ovarian cancer.

Talk with your doctor about your risk factors for ovarian cancer and what you can do about them.

Talk with your doctor about genetic counseling if you're concerned about your family's history of cancer and that it might be linked to an increased risk of ovarian cancer. You can talk about your choices to help decrease your chances of having this cancer if you do have gene changes that put you at higher risk.