Different types of Ovarian Cancer are classified according to the type of cell from which they start.
About 90 percent of Ovarian Cancers develop in the epithelium, the thin layer of tissue that covers the ovaries. This form of Ovarian Cancer generally occurs in postmenopausal women.
Germ cell carcinoma tumors
Making up about 5% of Ovarian Cancer cases, this type begins in the cells that form eggs. While germ cell carcinoma can occur in women of any age, it tends to be found most often in women in their early 20s. Six main kinds of germ cell carcinoma exist, but the three most common types are: teratomas, dysgerminomas, and endodermal sinus tumors. Many tumors that arise in the germ cells are benign.
Stromal carcinoma tumors
Ovarian stromal carcinoma accounts for about 5% 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% of stromal carcinoma cases are diagnosed in Stage I.