Ovarian cancer is an especially scary disease. Unlike many other cancers, the symptoms of ovarian cancer—among them pelvic pain, frequent urination, and bloating—tend to be vague. By the time a woman suspects something is wrong and visits her doctor, the cancer is often in a late, less curable stage. In fact, only 20% of ovarian cancers are discovered in the earliest stages.
This year, the National Cancer Institute predicts that 22,530 new cases of ovarian cancer will be diagnosed. Yet only 47.6% of women with the disease are alive five years after diagnosis; 13,980 are expected to die of the disease by the end of 2019. No wonder ovarian cancer has been dubbed the "silent killer."
Ovarian cancer isn't just one disease, however. There are more than 30 subtypes, and those subtypes are grouped under three main ovarian cancer types. “Ovaries are composed of many different types of cells, each which can transform and become cancerous,” Jack Jacoub, MD, medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast Medical Center in Fountain Valley, California, tells Health.
Here's what all women need to know about the three main types of ovarian cancer—and what makes them different from one another.
Epithelial ovarian cancer
Epithelial ovarian cancer is the most common type of ovarian cancer, comprising up to 90% of all ovarian cancer cases, according to the American Cancer Society (ACS).
It starts in the epithelial cells that line the outer surface of the ovaries. The cells here turn over and regenerate so frequently, and “that can lead to a higher rate of error in the way they divide, which adds to the propensity for something to go wrong and potentially form a cancer,” Sarah Taylor, MD, gynecological oncologist with Hillman Cancer Center/Magee-Womens Hospital of UMPC in Pittsburgh, tells Health.
Epithelial ovarian cancer also includes cancers that arise from the fallopian tubes and the lining of the abdomen and pelvis, known as the peritoneum. The most common subtype of this type of ovarian cancer is high-grade serious carcinoma, and is believed to start in one of the fallopian tubes.
Germ cell ovarian cancer
Germ cell ovarian cancer cases make up less than 2% of all ovarian cancer diagnoses, according to the ACS. In the simplest of terms, “germ cells are the cells that form eggs,” Dr. Taylor explains. This type of ovarian cancer often affects just one ovary. It primarily strikes women under 30. More than 9 out of 10 women diagnosed with this form survive at least 5 years after being diagnosed.
The most common subtype of germ cell ovarian cancer is a dysgerminoma, which tends to grow slowly. Another type is called a grade 1 immature teratoma, which is mostly benign with just a few spots of cancer.
Stromal ovarian cancer
Stromal cells are “support cells,” says Dr. Taylor. These cells form the connective tissue that hold each ovary together. Stromal cells also produce estrogen and progesterone.
Like germ cell tumors, stromal tumors (also known as sex cord-stromal tumors) are rare. Just 1% of all ovarian cancer cases are stromal ovarian cancer, and more than half of all cases are discovered in women in age 50. Still, about 5% of cases are found in young girls.
Some stromal cell tumors, such as fibromas, are usually benign. Others, like a subtype called granulosa cell tumors, are more likely to be malignant.
Because stromal tumors are hormonally active, abnormal vaginal bleeding is often a symptom.
Symptoms of each type of ovarian cancer
For the most part, the symptoms are the same for all three main types of ovarian cancer, and they can be frustratingly hard to detect early on. "They can be so non-specific that women overlook them,” Dr. Jacoub notes.
According to the National Ovarian Cancer Coalition, the most common symptoms include bloating, belly or abdominal pain, trouble eating or feeling full quickly, an urgent need to pee, exhaustion, back pain, pain during sex, nausea, heartburn, constipation, and changes in your period.
If you have any of these symptoms for more than 2 weeks, have them checked out by your primary care doctor. If she suspects there's a possibility you might have ovarian cancer, you’ll be referred to a gynecological oncologist.
How to lower your ovarian cancer risk
Despite all this scary-sounding info, “ovarian cancer is quite rare, effecting only about 1% of the population,” points out Dr. Taylor.
Your genes are a risk factor, so take a look at your family’s medical history. Finding out if any first-degree relatives (like your mom and siblings) have a history of cancer is a good start, but don’t stop there. “Your entire family history is important,” says Dr. Jacoub. “Sometimes there’s a scenario where a generation is skipped.”
If you do have a strong family history of breast and ovarian cancer, talk to your doctor. She may recommend that you see a genetic counselor.
Endometriosis and polycystic ovarian syndrome may also put you at risk for ovarian cancer, Dr. Jacoub says.
Another thing you can do to stay healthy? Stop putting off your yearly check-up. While you may dread pelvic exams, it’s a good way for your doctor to check the health of your ovaries. In the meantime, lead a healthy lifestyle by eating a balanced diet and getting plenty of exercise, suggests Dr. Taylor.