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A doctor explains epithelial ovarian tumors to a patient

All forms of ovarian cancer start in the female reproductive system, usually in one or both of the ovaries, which are grape-sized reproductive glands that produce eggs. However, recent research has revealed that some tumors classified as ovarian cancer actually start in the fallopian tubes, which are responsible for transporting eggs to the uterus for fertilization.

In either case, ovarian cancer most commonly develops in the epithelial cells, which are in the outer surface tissue of the ovaries or fallopian tubes. In fact, epithelial tumors account for 85% to 90% of all ovarian cancers.

Epithelial ovarian tumors are classified as one of the following:

  • Benign – These are noncancerous tumors that do not spread or cause serious health issues.
  • Borderline – Under a microscope, these tumors don’t clearly appear cancerous; they are slow-growing and considered less life-threatening than other ovarian cancers.
  • Malignant – This means the tumor is cancerous. Because it develops in the tissue lining of the ovaries or fallopian tubes, epithelial ovarian cancer is also classified as a carcinoma, as opposed to cancer that develops in the blood, lymphatic cells, or other parts of the body.

Types of epithelial ovarian cancer

Epithelial ovarian carcinomas can be broken down into many subtypes based on their cells’ features. They’re also graded according to how closely their cells resemble those of healthy tissue under a microscope, with grade 1 looking the most like normal tissue and grades 3 and 4 resembling normal tissue the least.

Here’s a brief look at the types of epithelial ovarian cancer that are most frequently diagnosed:

Serous ovarian cancer

High-grade (grade 3 or 4) serous carcinoma is the most common type of ovarian cancer. Its name includes "serous" because, in this type of cancer, the malignancy develops in the serous membrane of the epithelial layer of cells lining the patient’s abdominopelvic cavity.

Low-grade serous carcinoma, the fourth most common type of ovarian cancer, typically has slower-growing cancer cells than high-grade serous ovarian cancer.

Endometrioid ovarian cancer

Accounting for about 20% of all epithelial ovarian cancer cases, this type of cancer is often diagnosed in earlier stages than serous ovarian carcinoma. It is frequently diagnosed in patients who have a history of endometriosis.

Clear cell carcinoma

Also called “clear cell adenocarcinoma,” this is a rare type of epithelial ovarian cancer in which the cells look clear when viewed under a microscope. It is also thought to be related to endometriosis.

Mucinous carcinoma

One of the rarest forms of ovarian cancer, this subtype is characterized by tumors with abnormal mucus-secreting cells. It is the most frequent subtype of epithelial ovarian cancer diagnosed in women younger than 40.

Treatment for epithelial ovarian tumors

Doctors consider numerous factors when developing a patient’s treatment plan. For many cases of epithelial ovarian cancer, surgery would be the primary treatment option with some form of chemotherapy following. The surgical expertise and the integration of this in the treatment plan are key factors that can determine a patient’s survival from ovarian cancer. In some infrequent situations, chemotherapy might be the only primary treatment. Radiation therapy is not used as often with ovarian cancer as compared to other cancers, but it is occasionally recommended.

Immunotherapy is a more recently developed treatment that shows promise in fighting cancer, including malignant ovarian tumors. This type of therapy uses drugs to stimulate a patient’s immune system to better recognize and destroy cancer cells.

Reasons to choose Moffitt Cancer Center for ovarian cancer treatment

At Moffitt, our Gynecologic Oncology Program features a multispecialty team that includes medical oncologists, surgeons, radiation oncologists, fertility specialists and other professionals. Every member of the team specializes in treating ovarian cancer and works closely with other team members to develop individualized treatment plans for our patients.

Additionally, Moffitt is one of an elite group of cancer hospitals to be designated a Comprehensive Cancer Center by the National Cancer Institute. In fact, we’re the only Florida-based cancer center to receive this distinction. In addition to providing the highest level of cancer care for our patients, we’re also intently focused on research to develop new and effective treatment methods. As a result, our patients have access to clinical trials and treatments that aren’t readily available to cancer patients everywhere, and our survival rates are up to four times higher than the national average.

Medically reviewed by Robert Wenham, MD, Chair, Gynecologic Oncology Program

To learn more about epithelial ovarian tumors and treatment options, call Moffitt Cancer Center with or without a referral at 1-888-663-3488, or complete our new patient registration form online. Your cancer diagnosis is our top priority, and we want to support you with compassionate care through every step of your journey. Therefore, we’re connecting every new patient with a cancer expert as quickly as possible. 


National Cancer Institute – Ovarian Cancer Fallopian Tube Origins
Ovarian Cancer Research Alliance – High-Grade Serous Carcinoma
Cure Our Ovarian Cancer – Low-Grade Serous Ovarian Cancer
National Cancer Institute – Clear Cell Carcinoma
National Institutes of Health – Mucinous Cancer of the Ovary