Understanding Mucinous Ovarian Cancer, So You Can Spot It Early

Mucinous ovarian cancer (MOC) is a kind of epithelial ovarian cancer. This type of cancer begins in the cells that line the surface of the ovary. According to the American Cancer Society, 85% to 90% of ovarian cancers are epithelial.

Overall, MOC is rare. In fact, it only makes up about 6% of epithelial ovarian cancers.

MOC cells make mucus, a thick, protective substance that’s typically found in the gastrointestinal (GI), urogenital, and respiratory systems. Mucinous ovarian tumors are filled with this fluid.

MOC can be either of primary or metastatic origin:

• Primary: Primary MOC begins in an ovary. According to research, this happens when healthy cells transform into cancerous cells over time.
• Metastatic: Metastatic MOC happens because cancer that started somewhere else in the body, like the gastrointestinal (GI) tract, spread to an ovary.

It’s often challenging for doctors to distinguish between the two origins.

Under a microscope, most MOCs are heterogeneous. This means tumors can contain a mixture of cancerous, benign, and borderline cells. Borderline cells are cells that appear abnormal but aren’t yet cancerous.

MOC tumors can get very large. In fact, the average size of a mucinous ovarian tumor at presentation is 18 centimeters. That’s somewhere between the size of a cantaloupe and a basketball.

Primary tumors typically affect only one ovary. Metastatic tumors are smaller and often affect both ovaries.

The symptoms of MOC are similar to other ovarian cancers. Common symptoms can include:

• a lump on one side of your abdomen
• weight gain
• pain in your abdomen or pelvis
• abdominal bloating
• frequent or urgent urination
• feeling full quickly after eating

Other potential symptoms can be:

• fatigue
• irregular or heavier periods
• pain during sex
• back pain
• constipation
• stomach upset
• unintentional weight loss

Many symptoms of ovarian cancer are similar to other conditions that affect tissues in the abdomen or pelvis. What’s important to look out for are symptoms that:

• get worse over time
• continue to stick around
• happen more frequently
• are more severe than usual

People who get MOC are typically younger than those who develop other types of ovarian cancer. For example, according to a 2019 research article, the average age of diagnosis for MOC is 45 years.

According to a 2020 review, MOC also doesn’t have the same types of risk factors as other types of ovarian cancer. Right now, smoking is the only risk factor associated with this type of cancer.

The diagnostic process begins with a doctor getting your medical history and performing a physical exam. They will ask about your symptoms, when they began, and how long you’ve had them. They’ll also do a pelvic exam to feel for a mass in the area of the ovaries.

If ovarian cancer is suspected, your doctor will order additional tests. These can include:

• Imaging tests: Imaging tests can help your doctor get a look at what’s going on in your body. Some of the types of imaging tests that may be used to diagnose ovarian cancer are:
  • ultrasound, often a transvaginal ultrasound
  • CT scan
  • MRI scan
• Blood tests: These tests involve collecting a sample of blood from a vein in your arm and can include:
  • tests for ovarian cancer tumor markers, such as CA-125, CA19-9, and CEA
  • complete blood count, which measures the levels of different blood cells
  • metabolic panel, which assesses liver and kidney function as well as other factors associated with overall health
• Upper GI endoscopy or colonoscopy: Because MOC may originate from cancers in the GI tract, your doctor may use an upper GI endoscopy or a colonoscopy to look for a primary tumor.
• Biopsy: A tissue sample, or biopsy, is needed to make the diagnosis of ovarian cancer. This sample is collected from the tumor and is examined in a laboratory.

A biopsy is also vital for characterizing the features of a tumor to see whether they’re consistent with MOC. This includes looking at various markers to see if cancer started in the ovary or at another location.

Ovarian cancers, including MOC, are often treated with surgery. Many times, MOC is diagnosed in its earlier stages, so surgery may be the only treatment needed.

The extent of the surgery depends on how far the cancer has spread. Surgery for ovarian cancer can involve the removal of some or all of the following:

• one or both ovaries
• one or both fallopian tubes
• uterus
• cervix
• nearby lymph nodes
• omentum, a fatty fold of tissue in the abdomen

Your doctor may also order something called peritoneal washing to see whether the cancer has spread into the abdominal cavity. This procedure uses a saltwater solution to wash the abdominal cavity. The solution is then removed to check for cancer cells.

Because MOC can arise from cancers in the GI tract, appendectomy may be recommended as a part of surgery for these cancers. This is the surgical removal of the appendix.

For more advanced MOC, platinum-based chemotherapy may be recommended after surgery. However, MOC isn’t very responsive to chemotherapy.

Other treatment options for MOC may be available in the future. As a 2020 study notes, these cancers can be well suited for targeted therapy drugs.

Most ovarian cancers don’t begin to cause symptoms until they’ve begun to spread. Because of this, they’re typically diagnosed at more advanced stages.

This is often not the case with MOC. Because MOC tumors can grow to a large size, they can begin to cause symptoms earlier. The result is often a timelier diagnosis.

According to a 2020 review, 80% of MOCs are stage 1 at diagnosis. Researchers note early stage MOC has an overall relative 5-year survival rate of over 90%.

A small 2016 study further illustrates this point. Researchers compared overall survival of primary MOC with overall survival of primary serous cancer, the most common type of ovarian cancer. The relative 5-year survival rate of people with MOC was 100% compared with 58% in those with serous cancer.

The outlook for people with advanced or metastatic MOC is not nearly as good. In these cases, life expectancy generally ranges between 12 and 30 months. A 2015 study found that just 11% of people with these types of cancer survive for longer than 5 years.

MOC is a rare type of ovarian cancer. It causes tumors made from mucus-producing cells. These tumors can grow to be very large. MOC can either begin in the ovary or happen when another type of cancer spreads.

Because the tumors grow so large, most MOC cases are diagnosed in the early stages. When this happens, the outlook is typically excellent. However, advanced or metastatic MOC has a much poorer outlook.

The common symptoms of MOC can include abdominal or pelvic pain, bloating, and feeling a lump on one side of the abdomen. Don’t hesitate to talk with a doctor if these symptoms are persistent, occur frequently, or become severe.