Ovarian Tumor Types

Ovarian cancer can develop in the ovaries, the fallopian tubes, or the peritoneum, which is the tissue that surrounds the organs in the abdominal cavity. Cancers of the fallopian tube and peritoneum are regarded as ovarian cancers, because they require the same therapies and appear the same under the microscope. Ovarian tumors are classified according to the type of cells they develop in. It is important to understand not all tumors in the ovaries or surrounding tissues are cancerous.

Epithelial tumors

Most ovarian tumors are epithelial tumors. They develop in epithelial cells, which form the outermost layer of ovarian tissue. There are three different types of ovarian epithelial tumors:

  • Benign,
  • Low malignant potential, and
  • Malignant.

Benign

The majority of epithelial tumors are benign. This means they are not cancerous and will not spread. Benign epithelial tumors are generally straightforward to remove surgically, and patients don’t need further treatment.

Tumors of low malignant potential

Some epithelial tumors grow slowly. While they are not benign, and have the ability to become cancerous, they are also unlikely to spread to the rest of the ovary or beyond it into the surrounding tissue. Physicians classify these tumors as “tumors of low malignant potential,” meaning it is the kind of cancer that tends to not become worse or widespread. Like benign tumors, they can be removed through surgery.

Malignant

Even though malignant epithelial tumors are less common than benign epithelial tumors, they are most often the cause of ovarian cancer, making up 85 to 95 percent of cases in women. They grow more rapidly than other epithelial tumors and have the potential to metastasize to other areas of the body.

Patients with malignant epithelial tumors are treated with surgery as well as chemotherapy.

Germ cell tumors

 Germ cell tumors develop in the early cells that become eggs within the ovary. They can be either benign or malignant. Malignant germ cell tumors are rare, making up only 2 percent of ovarian cancers. Treatment for malignant ovarian germ cell tumors often includes surgery and chemotherapy.

Ovarian stromal tumors

Ovarian stromal tumors can also be benign or malignant. Malignant ovarian stromal tumors are the rarest cause of ovarian cancer and make up only 1 percent of cases. They develop in stromal tissue, which often will produce hormones, such as estrogen and progesterone.