Approximately 75 - 80% of ovarian tumors originate from

Approximately 75 - 80% of ovarian tumors originate from
a) Epithelium
b) Stroma
c) Germ cells
d) Mesoderm
e) Unclassified tissue

A.
Ovarian cancers are histologically diverse (see Table 1: Gynecologic Tumors: Types of Ovarian Cancers). At least 80% originate in the epithelium; 75% of these cancers are serous cystadenocarcinoma. The remaining 20% of ovarian cancers originate in primary ovarian germ cells or in sex cord and stromal cells or are metastases to the ovary (most commonly, from the breast or GI tract). Germ cell cancers usually occur in women < 30.

Ovarian cancer spreads by direct extension, exfoliation of cells into the peritoneal cavity (peritoneal seeding), lymphatic dissemination to the pelvis and around the aorta, or, less often, hematogenously to the liver or lungs.