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Grades and Types of Ovarian Cancer

There are three grades of ovarian cancer:

  • Grade 1 is “well-differentiated”
  • Grade 2 is “moderately differentiated”
  • Grade 3 is “poorly differentiated”

The lower the grade, the slower the cancer cells grow.

There are several different tumor types in ovarian cancer:

  • Epithelial tumors - Approximately 90 percent of ovarian cancers develop in the epithelium, the thin layer of tissue that covers the ovaries and makes up the fallopian tubes. This form of ovarian cancer generally occurs in postmenopausal women.
  • Germ cell carcinoma tumors - Approximately five percent of ovarian cancer cases begin in the cells that form eggs. While germ cell carcinoma can occur in women of any age, it is found most often in women who are in their early 20s. Many tumors that arise in the germ cells are benign.
  • Stromal carcinoma tumors - Ovarian stromal carcinoma accounts for about five percent of ovarian cancer cases. It develops in the connective tissue cells that hold the ovary together and those that produce the female hormones estrogen and progesterone. The two most common types are granulosa cell tumors and sertoli-leydig cell tumors. Unlike with epithelial ovarian carcinoma, 70 percent of stromal carcinoma cases are diagnosed in stage I.
  • Small cell carcinoma of the ovary - Small Cell Carcinoma of the Ovary (SCCO) is a rare, highly malignant tumor that affects mainly young women, with a median age at diagnosis of 24 years old. The subtypes of SCCO include pulmonary, neuro-endocrine and hypercalcemic. SCCO accounts for 0.1% of ovarian cancer cases.

For a more detailed look at the staging for ovarian cancer, visit FIGO Ovarian Cancer Staging. This staging was revised and approved for ovarian cancer in January 2014 by the International Federation of Gynecologists and Obstetricians (FIGO).