An ovarian tumor is a growth of abnormal cells that may be either
noncancerous (benign) or cancerous (malignant). Although benign tumors
are made up of abnormal cells, these cells don't spread to other body
tissues (metastasize). Malignant cells metastasize and may spread
directly into other tissues, or may detach from the original tumor site
and spread through your body by way of blood vessels or lymph nodes.
Although the exact cause of ovarian cancer is unknown, three basic types
of tumors exist and are designated by where they form in the ovary. They
About 90 percent of ovarian cancers develop in the epithelium, the
thin layer of tissue that covers the ovaries. This is the most
common form of ovarian cancer and generally occurs in postmenopausal
These tumors occur in the egg-producing cells of the ovary and
generally occur in younger women.
These tumors develop in the estrogen- and progesterone-producing
tissue that holds the ovary together.
Several factors may increase a woman's risk of ovarian cancer. Having
one or more of these risk factors doesn't mean that you're sure to
develop ovarian cancer, but your risk may be higher than that of the
average woman. These risk factors include:
This is the most important risk factor for ovarian cancer. A family
history of ovarian cancer in a first-degree relative — mother,
daughter or sister — increases your risk of developing the disease.
The likelihood is greater if two or more first-degree relatives have
had ovarian cancer. A family history of breast or colorectal cancer
also is associated with an increased risk of ovarian cancer.
Ovarian cancer generally develops after menopause, and women older
than 60 are at highest risk. Although most cases of ovarian cancer
are diagnosed in older women, the disease can also occur in younger
Women who have had at least one pregnancy appear to have a lower
risk of developing ovarian cancer. Similarly, the use of oral
contraceptives appears to offer some protection against ovarian
If you've had trouble conceiving or had your first child late in
life, you may be at increased risk.
Some women who develop ovarian cysts have no symptoms, but have cysts
that are found by their physician during a pelvic examination. Cyst
formation is a normal part of ovulation in premenopausal women. However,
cysts that don't go away or that occur after menopause need to be
evaluated. Doctors don't know if these benign ovarian cysts develop into
ovarian cancer, but it's recommended that they be removed. Types of
ovarian cysts include:
These cysts are actually benign tumors called teratomas. They may
contain tissue such as hair, skin or teeth because they form from
cells that produce human eggs. They're seldom cancerous, but can
become large and cause painful twisting of the ovary and fallopian
If you have endometriosis, a condition in which uterine cells grow
outside your uterus, some endometrial tissue may attach to the ovary
and form a cyst.
These cysts develop from ovarian tissue and may be filled with a
watery liquid or a mucous material. They can become large and cause
twisting of the ovary and fallopian tube.
No test can determine with perfect accuracy whether an ovarian cancer
growth or cyst is benign or malignant. However, the following
characteristics can help your doctor in assessing an ovarian growth:
Size of the
A small percentage of growths smaller than about 2 inches in
diameter are cancerous. The likelihood of cancer increases with the
size of the growth. Your risk of ovarian cancer can be more than 60
percent when a growth is larger than 4 inches.
If you're 50 or older, the likelihood that your cyst is malignant is
25 percent. Once you reach your 80s, the chance increases
Only about 10 percent of postmenopausal ovarian cysts are normal
monthly (functional) cysts. The remainder are tumors that can be
either benign or malignant. Doctors don't know why ovarian cysts
form after menopause.
Although the majority of cases of ovarian cancer occur in women who
don't have a strong family history of the disease, a small number of
ovarian cancer cases are linked to a genetic predisposition for the
Other factors may play a role in a woman's increased risk of ovarian
cancer. More research is needed to confirm these findings. These factors
Researchers are exploring a possible role of fertility drugs — which
are used to cause ovulation — in increasing the risk of ovarian
replacement therapy (HRT).
Women who use HRT after menopause may be at increased risk of
developing ovarian cancer. HRT may have other negative effects as
well. Taking HRT as a combination therapy — estrogen plus progestin
— can result in serious side effects and health risks. If you're
considering HRT, work with your doctor to evaluate the options and
decide what's best for you.
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