An Overview of Ovarian Cancer

Symptoms, Causes, Diagnosis, and Treatment

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Ovarian cancer has been coined the "silent killer" due to its lack of notable symptoms until the condition is fairly advanced when it can cause painful intercourse, unexplained weight gain, and more. The average lifetime risk of developing this cancer is just 1.6 percent, but since the disease often goes undetected until it reaches the advanced stages, it is the fifth most common cause of cancer-related deaths in women.

Treatments such as surgery and chemotherapy may be used, though their success decreases the more advanced the disease becomes.

Types

The female reproductive system consists of the vagina, the cervix (the lower portion of the uterus), the uterus, two fallopian tubes, and two ovaries. The ovaries are roughly the size of an almond and are responsible for the development and release of an egg with each menstrual cycle. They are also responsible for the production of the hormones estrogen and progesterone

Ovarian cancer usually begins in the part of the fallopian tube closest to an ovary and then spreads to that ovary. The disease may also sometimes begin in the peritoneum, the membranes the surround the contents of the abdomen, and then spread to an ovary. For that reason, ovarian cancer, cancer of the fallopian tubes, and primary peritoneal cancer are often grouped together when discussing these cancers.

There are three basic categories of ovarian cancer (though there are more than 30 subtypes). These different types may be treated in different ways, have a different prognosis, and occur in women of different ages in general.

  • Epithelial ovarian tumors arise from the layer of cells (the epithelial layer) lining the ovaries and fallopian tubes and account for 90 percent to 95 percent of ovarian cancers. The risk of these cancers increases with age, and most people are postmenopausal when diagnosed. The most common subtypes include endometrioid, mucinous, and serous tumors, with the majority being serious. Mucinous and endometrioid tumors are more common in women under age 40. 
  • Stromal tumors can be either benign or malignant and begin in the stroma, the tissue that surrounds the egg and holds the ovaries together. These are broken down into several subtypes, including granulosa cell tumors—which are aggressive in the juvenile form, found between birth and age 20, but usually non-aggressive in the adult form—and Sertoli cell tumors.
  • Germ cell tumors can also be either benign or malignant and are the most common form of ovarian cancer in those under 30. Most are diagnosed between ages 10 and 30. These tumors begin in the reproductive cells (the egg) and account for around 3 percent of ovarian cancers. Germ cell tumors are often diagnosed in the early stages but tend to grow rapidly. A few of the subtypes include dysgerminomas, endodermal sinus tumors, and immature teratomas
  • Small cell carcinoma of the ovary is uncommon, making up only 0.1 percent of ovarian cancers.

The median survival rate for high-grade epithelial ovarian cancer (all stages combined) is five years, but roughly 15 percent of people diagnosed are alive after 10 years. Researchers are now studying these "outliers" in hopes of finding better ways to treat the disease. Prognosis for individuals is dependent on many factors, such as age, stage and tumor grade of cancer, the response to treatment, and much more.

Symptoms

The symptoms of ovarian cancer are often subtle and vague in the early stages of the disease and are often attributed to other, less serious conditions. Even though around 80 percent of these cancers are already at an advanced stage when diagnosed, recent research has found four symptoms that are common in the earlier stages. These include:

  • Changes in bowel habits, like constipation or diarrhea
  • Pelvic pain or pressure
  • A frequent need to urinate or urinary urgency
  • Bloating or abdominal swelling

Some symptoms of ovarian cancer often do not appear until the disease has progressed. These can include pain during sexual intercourse, persistent fatigue, abdominal weight gain or fluid build-up (ascites), among others.

Other symptoms are due specifically to hormones produced by the tumor, including deepening of the voice, facial hair growth, and abnormal uterine bleeding.

Causes and Risk Factors

Unfortunately, we cannot pinpoint exactly what causes ovarian cancer, but researchers have identified several known risk factors for its development. While risk factors are important, it's important to keep in mind that ovarian cancers may occur in people who have no risk factors or family history of the disease. 

Risk factors include, but are not limited to, advanced age; Caucasian ethnicity; a family history of ovarian, breast, or colon cancer; obesity; and unopposed estrogen replacement therapy.

Factors associated with a lower risk of ovarian cancer include, but are not limited to having a child before the age of 26, breastfeeding, oral contraceptive use, tubal ligation surgery, and hysterectomy.

Ovarian cancer is less common in young women. When it occurs, there is often a family history and it's more likely to be related to hereditary factors such as BRCA1 or BRCA2 mutations. Ovarian cancer is the fifth most common cancer diagnosed during pregnancy and occurs in 1 in 18,000 pregnancies.

Diagnosis

Ovarian cancer is not routinely screened for. Diagnosing ovarian cancer often requires a high index of suspicion on the part of a doctor to prompt the ordering of imaging and lab tests that can indicate the disease.

Doctors typically order a transvaginal ultrasound and a CA-125 blood test first, though the latter can be normal in some people with early ovarian cancer and may be elevated by many other medical conditions. A doctor may initiate these tests after performing a routine pelvic exam, or a person may present with symptoms of or metastases (spread) from the tumor that prompt these next steps.

Other imaging tests, such as CT, MRI, and PET scans, along with other blood tests may then be ordered (primarily to see if cancer, if present, has spread). A biopsy is needed both to confirm the diagnosis and identify the type of ovarian cancer found.

After diagnosis, staging of the tumor is very important in order to determine the most appropriate treatment options. This can be done with a combination of tumor findings on the biopsy sample and imaging studies, but often requires surgery.

Treatment

Treatment options for ovarian cancer depend on the type, stage, and grade of ovarian cancer, as well as other factors such as age and general health.

There are three primary treatment methods for ovarian cancer. Surgery combined with chemotherapy is the most common treatment course for all but the earliest stages of the disease. Radiation therapy is not commonly used but may be recommended for some women with extensive metastases in their abdomen.

  • Surgery: Removal of the ovary and fallopian tube on one side may be considered for those who hope to preserve their fertility. Debulking or cytoreduction surgery may be considered to remove as much of the tumor (and metastases) as possible in order to increase the effectiveness of chemotherapy.
  • Chemotherapy: Chemotherapy is used to eliminate cancer cells that remain after surgery, or to reduce the risk of recurrence when no obvious cancer cells remain. It can also be given alone as palliative chemotherapy to reduce symptoms.
  • Targeted therapy: This involves treatment with drugs that target specific pathways in the growth of cancer cells. Because of their focus, they often, but not always, have fewer side effects than conventional chemotherapy drugs. There are two types of target therapies: those aimed at inhibiting the formation of new blood vessels by tumors, and those that target a pathway in cancer cell growth.

Clinical trials are in progress studying combinations of the above therapies, as well as newer therapies, such as immunotherapy drugs. According to the National Cancer Institute, people who are diagnosed with ovarian cancer should consider taking part in a clinical trial.

A Word From Verywell

At the current time, most epithelial ovarian cancers are diagnosed in the later stages of the disease. Since we do not have a recommended screening test, it's important to be aware of the symptoms and seek medical attention if you experience any of them—even if you think they are probably nothing.

If you or a loved one have recently been diagnosed with ovarian cancer, you may feel very frightened as you look at the statistics surrounding the disease. Despite these sobering numbers, treatments for the disease are improving as are survival rates, and many of today's clinical trials are looking for newer and better ways to treat patients.

Sources:

Hoppenot, C., Eckert, M., Tienda, S., and E. Lengyel. Who Are the Long-Term Survivors of High-Grade Serous Ovarian Cancer?. Gynecologic Oncology. 2018. 148(1):204-212.

National Cancer Institute. Ovarian Epithelial, Fallopian Tube, and Primary Peritoneal Cancer Treatment (PDQ)—Health Professional Version. Updated 01/19/18. https://www.cancer.gov/types/ovarian/hp/ovarian-epithelial-treatment-pdq