Can an Ovarian Cyst Be Cancerous?

Certain risk factors increase the odds of a malignancy

Woman being shown a chart by her doctor
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In This Article

Ovarian cysts are fluid-filled sacs that develop in and on the ovaries. They can affect women of all ages and are most often benign. The causes of ovarian cysts vary by whether you are still having periods (premenopausal) or have stopped having periods (postmenopausal). In premenopausal women, ovarian cysts are less likely to be cancerous and more likely the result of normal ovulation and other causes. In postmenopausal women, new growths are somewhat more likely to be cancerous; even so, the vast majority of cysts will be benign.

If ovarian cancer is suspected, the doctor will perform a battery of tests, which includes a pelvic exam, transvaginal ultrasound, and blood tests. If cancer is diagnosed, surgery is commonly performed to remove the tumor. Treatment may also involve chemotherapy, hormone therapy, radiation therapy, and newer targeted therapies.

Types of Ovarian Cysts

In most women, cancer is a rare cause of an ovarian cyst. There are numerous other possible explanations, particularly if you are premenopausal. The risk of ovarian cancer tends to increases with age, with most cases occurring after menopause.

Common causes of ovarian cysts in premenopausal women are:

  • Ovulation: A "functional cyst" can develop when a follicle does not rupture and release an egg during ovulation. It can also develop as the corpus luteum is being formed after ovulation. These cysts are common and benign, and will typically resolve on their own without treatment.
  • Dermoid Cysts: Also known as teratomas, these cysts are most commonly seen in women between 20 and 40 and are caused when fetal skin cells become trapped in ovarian tissues. The vast majority are benign.
  • Pregnancy: An ovarian cyst can commonly develop in early pregnancy until the placenta is fully formed. In some cases, the benign cyst may persist until later in the pregnancy.
  • Severe Pelvic Infection: Ovarian cysts that develop during a severe pelvic infection are caused by the accumulation of pus in ovarian tissue. A course of antibiotics may be needed to resolve the infection.
  • Polycystic Ovary Syndrome (PCOS): PCOS is a hormonal disorder commonly affecting women of reproductive age. It causes the enlargement of the ovaries and the formation of multiple cysts on the outer edges.
  • Endometriosis: Endometriosis is a disorder in which the lining of the uterus (endometrium) extends beyond the uterus. It often causes the formation of cysts called endometrioma (also known as "chocolate cysts").
  • Non-Cancerous Growths: These include fibromas comprised of connective tissues and fluid-filled cystadenomas that form on the outside of the ovaries and can become quite large.
  • Ovarian Cancer: In premenopausal women, less than 1% of new growths on or in an ovary will turn out to be cancer.

The picture is slightly different for postmenopausal women. Common causes of ovarian cysts in postmenopausal women include:

  • Cystic Lesions: Ovarian cysts of less than 1 centimeter (0.4 inches) in size are common in postmenopausal women, the vast majority of which will be benign.
  • Intrauterine Fluid Accumulation: This is a common phenomenon in late postmenopausal women, which can trigger swelling of the ovaries along with the formation of ovarian cysts.
  • Ovarian Cancer: Around 90% of ovarian cancers occur in women over 45 and 80% occur in women over 50. The vast majority are diagnosed between the ages of 60 to 64.

Despite the increased incidence of ovarian cancer in postmenopausal women, the lifetime risk is still relatively low, affecting around one of 327 women (0.3%) by her 60s and one of 283 women (0.4%) by her 80s.

Risk Factors

There are characteristics of an ovarian cyst that make it more likely to be cancerous as well as risk factors that can increase a woman's odds of a malignancy.

Ovarian cancer is more likely in women with:

  • A family history of ovarian, gastrointestinal, or breast cancer, especially first-degree relatives (like parents or siblings) who developed cancer at an early age
  • A previous history of breast or gastrointestinal cancer
  • A genetic predisposition for ovarian cancer (as indicated by mutations of the BRCA1 and BRCA2 genes) in whom the lifetime risk of ovarian cancer is between 10% and 60%
  • An ovarian cyst over 5 centimeters (2 inches) that is irregular in shape and/or has solid areas
  • Multiple cysts on both ovaries
  • Ascites (an accumulation of fluid in the pelvis or abdomen)

Age also plays a role but does not exclude premenopausal women of whom one in 870 (0.1%) are at risk of cancer.

Abnormal ovarian cysts are commonly referred to as pathologic cysts in lab reports. This does not mean that the cyst is cancerous, but simply that it is unusual in its shape, size, or consistency. Most pathologic cysts are benign.

Symptoms

Symptoms alone cannot predict whether an ovarian cyst is cancerous or benign. Many women with ovarian cancer will experience few if any symptoms, particularly in the early stages. If there are symptoms, they are often non-specific and easily attributed to other less serious conditions.

Women with ovarian cancer will often have vague abdominal symptoms, including:

  • Persistent abdominal distension
  • A persistent feeling of full
  • Loss of appetite
  • Pelvic or abdominal pain
  • An increased need to urinate
  • A feeling that you need to urinate constantly

Where these symptoms become increasingly relevant is in women over 50. The development of these symptoms in postmenopausal women, along with a significant family history of breast or ovarian cancer, strongly indicates a need for further testing.

Diagnosis

Most ovarian cysts are found during an annual pelvic exam. If one is found and ovarian cancer is suspected, the doctor will start the diagnosis by reviewing your family history, medical history, symptoms, and risk factors.

The evaluation may also involve a rectovaginal exam in which a finger is inserted into the vagina and another into the rectum to get a better sense of the size and consistency of the cyst.

Women at high risk of ovarian cancer or with an abnormal pelvic exam will commonly undergo a battery of minimally invasive tests, including:

  • Transvaginal Ultrasound: This involves the insertion of a wand-like device into the vagina that can image tissues using sound waves. It is the single most effective way of imaging and characterizing ovarian cysts.
  • CA-125 Test: This blood test measures the level of a protein called CA-125 that is secreted by ovarian cancer cells. While useful in supporting a cancer diagnosis in high-risk women, CA-125 levels can also be increased during menstruation, in women with uterine fibroids, or those with other types of cancers (such as endometrial and peritoneal cancer).
  • Magnetic Resonance Imaging (MRI): This imaging technology uses powerful radio and magnetic waves to create highly detailed images of soft tissue and can help better characterize the structure of an ovarian cyst.

Computed tomography (CT) scans tend to be less sensitive than MRIs and less useful in the initial diagnosis of ovarian cancer. Similarly, blood tests commonly used to diagnose other forms of cancer, like carcinoembryonic antigen (CEA), and cancer antigen 72-4 (CA72-4), are less helpful in women with ovarian cancer.

To confirm a cancer diagnosis, the doctor will perform a biopsy in which a sample of tissue is removed from the cyst for evaluation in the lab. There are several types of biopsy a doctor may use:

  • Fine Needle Aspiration (FNA): This involves the insertion of a 21- to 25-gauge needle through the skin and into the cyst to withdrawal a tiny sample of cells.
  • Core Needle Biopsy: This employs a larger needle to extract a cylinder of tissue about 1/2 inch long and 1/8 inch in diameter.

In some cases, a tissue sample may be performed during a pelvic laparoscopy, a minimally invasive procedure in which a narrow scope is inserted through a tiny incision in the abdomen to view the reproductive organs.

These procedures are not only critical to the diagnosis of ovarian cancer but can also help avoid unnecessary surgery until the malignancy is definitively diagnosed.

In the United States, around 5% and 10% of women will undergo surgical evaluation of an ovarian cyst, of which 13% to 21% of the investigations will reveal cancer.

Treatment

Most women diagnosed with ovarian cancer will undergo some form of surgery to remove the tumor. Depending on the type and stage of ovarian cancer involved, other forms of treatments may be recommended, either before or after surgery (or both).

Surgery

The main goal of ovarian cancer surgery is to remove as much of the tumor as possible, referred to as debulking. This may involve removing nearby tissue, including parts of the colon, small intestine, bladder, liver, spleen, bladder, or pancreas.

Many women with ovarian cancer will undergo hysterectomy with bilateral salpingo-oophorectomy in which the uterus, both ovaries, and both fallopian tubes are surgically removed.

If cancer is limited to one ovary only, the unaffected ovary and fallopian tube may be preserved if you intend to have children.

Chemotherapy

Following surgery, aggressive chemotherapy is the mainstay of treatment for most women. This usually involves a combination of drugs comprised of a platinum-based agent like cisplatin or carboplatin and another type of drug called a taxane, which includes Taxol (paclitaxel) and Taxotere (docetaxel).

Other drugs may be added to chemotherapy, the treatment of which is typically delivered intravenously (into a vein) every three to four weeks for three to six cycles.

Targeted Therapy

Targeted therapies are those that help kill cancer cells but cause minimal harm to normal tissues. These are often incorporated into chemotherapy. Options include:

  • Avastin (bevacizumab), which can shrink or slow the growth of a tumor by preventing the formation of new blood cells that nourish them
  • PARP inhibitors like Lynparza (olaparib), Rubraca (rucaparib), and Zejula (niraparib) that are typically used for advanced ovarian cancer

Hormonal Therapy

Hormonal therapy can be used to treat certain types of ovarian cancer or prevent their recurrence. These include hormones and drugs that block the action of estrogen, a female hormone that can influence the growth of certain cancers. Options include:

  • Luteinizing hormone (LH), which lowers estrogen levels in premenopausal women
  • Aromatase inhibitors like Femara (letrozole) and Aromasin (exemestane) that lowers estrogen levels in postmenopausal women
  • Tamoxifen, a drug more commonly used in hormone-sensitive breast cancer but one that may be useful in certain advanced ovarian cancers

Radiation

Radiation therapy is less commonly used to treat a primary ovarian tumor and is more often employed to treat areas where cancer has metastasized (spread). This typically involves external beam radiation therapy (EBRT) in which a narrow beam of ionizing X-ray radiation is directed at cancerous tissues every three to four days for several weeks.

Brachytherapy, involving the implantation of radioactive seeds into tumors, is rarely used to treat ovarian cancer.

Prognosis

Depending on the type and stage of cancer involved, doctors can generally predict a woman's long-term outlook (referred to as the prognosis). This is standardly based on five-year survival rates, which estimates the percentage of women who will live for at least five years following diagnosis.

The prognoses are largely differentiated by whether the tumor is localized, regional (affected nearby tissues), or distant (metastasized).

According to the American Cancer Society, the current five-year survival rate for women with ovarian cancer is:

  • Localized: 92%
  • Regional: 76%
  • Distant: 30%

The outcome of surgery also plays a role in survival rates. Women whose ovarian tumor has been optimally debulked have a better outlook than women in whom tumor tissues remain.

A Word From Verywell

As scary as it may be to hear that you have an ovarian cyst⁠—or, even more specifically, a pathologic ovarian cyst⁠—it is important to remember that the majority are benign. Even so, it is important to have any abnormal growth checked out and regularly monitored in the unlikely event it becomes cancerous.

Even if a cyst turns out to be malignant, early diagnosis almost invariably confers to simpler treatments and better outcomes. Ever-improving therapies are likely to extend survival times in the coming years, even among women with advanced ovarian cancer.

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