Clear cell ovarian cancer is generally categorized as a more aggressive type of cancer that tends to grow and spread quickly.

Ovarian cancer begins in the ovaries, the glands that produce eggs used in reproduction. According to the American Cancer Society (ACS), this type of cancer is the fifth most common cause of cancer deaths in women.

This article covers how quickly clear cell ovarian cancer grows, the outlook for people with this type of ovarian cancer, and risk factors to be aware of.

The three types of ovarian cancer

There are three types of ovarian cancer. Each one corresponds to a different cell type found in the ovaries:

  • Epithelial: Epithelial ovarian cancer starts in cells that line the outside of the ovary. It’s the most common type of ovarian cancer.
  • Germ cell: Germ cell ovarian cancers begin in the cells that form the eggs used for reproduction.
  • Stromal: Stromal ovarian cancer starts in the connective tissue of the ovaries that makes hormones such as estrogen and progesterone.
Was this helpful?

Clear cell ovarian cancer is a rare subtype of epithelial ovarian cancer. According to the ACS, it makes up about 6% of ovarian cancers. You may also see it called clear cell carcinoma.

Clear cell ovarian cancer is classified as a type 1 ovarian tumor. Most type 1 ovarian tumors are low grade, which means they grow slowly.

But clear cell ovarian cancer is considered high grade. High grade tumors appear more abnormal under a microscope and tend to grow and spread more quickly.

Many people with clear cell ovarian cancer have a large mass affecting one ovary. Therefore, this type of cancer is most often diagnosed at an earlier stage.

An estimated 57–81% of clear cell ovarian cancers are diagnosed at stage 1 or stage 2. At these stages, the cancer is still localized to the area of the ovaries and can be more easily removed with surgery. The outlook for people with these cancers is positive overall.

How and where does clear cell ovarian cancer typically spread?

There are several ways that clear cell ovarian cancer may spread (metastasize) to other parts of your body, including through your bloodstream or lymphatic system and within your abdominal cavity.

According to a 2021 review, clear cell ovarian cancer most commonly spreads to the lymph nodes or other organs in the abdomen and pelvis, such as the uterus, abdominal lining, or liver. It may also spread to the lungs, bone, or brain.

Symptoms of ovarian cancer and when to see a doctor

Some of the potential symptoms of ovarian cancer are:

The symptoms above can also result from other, more common conditions. But if you develop symptoms that are persistent, recurring, or severe, it’s always a good idea to discuss them with a healthcare professional.

Was this helpful?

This cancer has a much better outlook when diagnosed at an early stage than when diagnosed at an advanced stage. This is because early stage clear cell ovarian cancers can generally be removed effectively with surgery.

Advanced ovarian cancers typically require systemic treatments such as chemotherapy in addition to surgery. Clear cell ovarian cancers can be challenging to treat because they’re more resistant to chemotherapy.

In fact, the effectiveness of platinum-based chemotherapy for this type of cancer is 20–50%. This can mean that the outlook for advanced clear cell ovarian cancers is quite unfavorable.

Survival rates for people with clear cell ovarian cancer

In a 2015 study that included 177 people with clear cell ovarian cancer, researchers found that the 3-year overall survival rate for all stages was 75.9%.

Most study participants (62.2%) had stage 1 disease, and their 3-year overall survival was 90.1%. The outlook was much less favorable for advanced disease, with 3-year overall survival rates of 53.3% and 29.6% for stages 3 and 4, respectively.

Clear cell ovarian cancer can also recur after treatment. In a 2019 study involving 209 people, 29% of participants had a recurrence. Recurrent clear cell ovarian cancer often happened at multiple sites and was associated with an unfavorable outlook.

New treatments for clear cell ovarian cancer

Because clear cell ovarian cancer is more resistant to the types of chemotherapy used for other ovarian cancers, researchers are looking for new treatments for this type of ovarian cancer.

Areas being investigated include immunotherapy with immune checkpoint inhibitors and targeted therapy that focuses on limiting blood vessel formation around tumors or inhibiting cells with mutations in the ARID1A gene.

New and emerging antibody drug conjugates are also being researched for the treatment of ovarian cancers.

Was this helpful?

An important risk factor for this type of cancer is endometriosis, which is believed to be a precancerous lesion for clear cell ovarian cancer. People with endometriosis have a three-fold higher risk of clear cell ovarian cancer than those without endometriosis.

Additional risk factors for clear cell ovarian cancer include:

  • starting your period at an earlier age
  • entering menopause at a later age
  • never having a full-term pregnancy

People with clear cell ovarian cancer typically receive a diagnosis at a younger age than people with other types of ovarian cancer. The median age at diagnosis for clear cell ovarian cancer is 55 years. In comparison, the median age is 64 years for the most common type of ovarian cancer, serous ovarian cancer.

Clear cell ovarian cancer also has a different prevalence based on geography, occurring more often in Asian countries such as Japan, Taiwan, and Korea than in North America and Europe. The exact reason for this isn’t known yet.

Clear cell ovarian cancer is a rare subtype of epithelial ovarian cancer. It’s classified as high grade, which means it can be more aggressive than low grade cancers.

However, in most cases, doctors diagnose clear cell ovarian cancer when it’s still in its early stages. The outlook for early stage clear cell ovarian cancer is positive, as it can often be removed with surgery.

The outlook for advanced or recurrent clear cell ovarian cancer is much less positive. This is largely because this cancer is more resistant to systemic chemotherapy.