- Risk Factors
Doctors cannot always explain why one person gets cancer and another does not. However, scientists have studied general patterns of cancer in the population to learn what things around us and what things we do in our lives may increase our chance of developing cancer.
Anything that increases a person's chance of developing a disease is called a risk factor; anything that decreases a person's chance of developing a disease is called a protective factor. Some of the risk factors for cancer can be avoided, but many cannot. For example, although you can choose to quit smoking, you cannot choose which genes you have inherited from your parents. Both smoking and inheriting specific genes could be considered risk factors for certain kinds of cancer, but only smoking can be avoided. Prevention means avoiding the risk factors and increasing the protective factors that can be controlled so that the chance of developing cancer decreases.
Although many risk factors can be avoided, it is important to keep in mind that avoiding risk factors does not guarantee that you will not get cancer. Also, most people with a particular risk factor for cancer do not actually get the disease. Some people are more sensitive than others are to factors that can cause cancer. Talk to your doctor about methods of preventing cancer that might be effective for you.
The purposes of this summary on ovarian cancer prevention are to:
- Give information on ovarian cancer and how often it occurs.
- Describe ovarian cancer prevention methods.
- Give current facts about which people or groups of people would most likely be helped by following ovarian cancer prevention methods.
You can talk to your doctor or health care professional about cancer prevention methods and whether they would be likely to help you.
Ovarian Cancer Prevention
The ovary is a female reproductive organ located in the pelvis. Its function is to produce female hormones and to store eggs that, if fertilized by sperm, can develop into a baby. Women have two ovaries, one on each side of the uterus.
Tumors found in the ovaries may be noncancerous tissue growths (cysts) or cancerous growths that may spread to other parts of the body.
Significance of ovarian cancer
In the United States, more women die of ovarian cancer each year than of cervical and endometrial cancers combined. Survival rates have not greatly improved, and screening has not been proven to decrease the death rate.
Ovarian cancer can sometimes be associated with known risk factors for the disease. Many risk factors are modifiable though not all can be avoided. Avoiding risk factors when possible and increasing protective factors may help prevent ovarian cancer.
Genetic Factors: Women who have inherited certain altered (mutated) genes have a much higher risk of developing ovarian cancer. These mutations may be found in BRCA1, BRCA2, or hereditary nonpolyposis colon cancer (HNPCC) genes. For more information on groups that are at high risk for ovarian cancer due to inherited genetic factors, see the PDQ summary on the Genetics of Breast and Ovarian Cancer.
Age: The risk of developing ovarian cancer increases as a woman gets older.
Obesity: Having excess body fat as measured by body mass index, including during the teen years, increases the risk of ovarian cancer. Diet and nutrition during the teen years may play a role in prevention.
Oral Contraceptives: Studies show that the use of oral contraceptives reduces the risk of developing ovarian cancer. The longer you use oral contraceptives, the lower your risk might be. The decrease in risk may last up to 25 years after the use of oral contraceptives has ended. This lower risk is seen both in women who have given birth and in women who have not. Oral contraceptives may also protect against ovarian cancer in women who are at higher risk because they have inherited an altered version of BRCA1 and BRCA2 genes.
Harms from taking oral contraceptives include:
- A higher risk of blood clots that can block blood vessels, especially in smokers.
- A slightly higher short-term risk of breast cancer that decreases over time when use is stopped.
Childbearing and Breast-feeding: Women who have had at least one child are less likely to develop ovarian cancer than women who have never had children. Studies have also shown that women who breast-feed are less likely to develop ovarian cancer.
Tubal Ligation or Hysterectomy: Studies have shown that women who have undergone tubal ligation (sterilization) or hysterectomy are at decreased risk of developing ovarian cancer.
Family History of Ovarian Cancer: A woman who has a first-degree relative (mother or sister) or a cluster of 2 or more relatives with ovarian cancer has a higher than average risk of developing ovarian cancer.
Prophylactic Oophorectomy: Sometimes women with a very strong family history of ovarian cancer decide to have prophylactic oophorectomy (removal of both ovaries) and salpingectomy (removal of the fallopian tubes). This greatly reduces the risk of ovarian cancer in women who have inherited an altered version of BRCA1 and BRCA2 genes or hereditary nonpolyposis colon cancer (HNPCC) genes. With prophylactic removal of the ovaries, there is still a small chance that ovarian cancer may develop in nearby abdominal and pelvic tissue. It is important to have a cancer risk assessment and counseling before making this decision.
Possible harms from prophylactic oophorectomy include:
- Loss of fertility, hot flashes, decrease in sexual interest, vaginal dryness, frequent urination, bone loss, and increased risk of heart disease.
- Risks from surgery, including bleeding, infection, damage to nearby organs, reactions to medications used, and the possibility of death.
Hormone Replacement Therapy/Hormone Therapy: Hormone replacement therapy, also called hormone therapy, is associated with an increased risk of ovarian cancer in postmenopausal women. The risk increases with the length of use, and may be different for estrogen-only therapy (ERT) and estrogen-progestin replacement therapy (EPRT).
Some studies show an increased risk of ovarian cancer in women who have used fertility drugs, especially in those who do not become pregnant. Other risk factors that have been suggested for ovarian cancer are the use of talcum powder in the area between the vagina and the anus, or eating a high fat or high lactose diet. The exact relationship remains unclear.