Chapter 97

### Incidence and Pathology

Ovarian cancer is the most lethal malignancy of gynecologic origin in the United States and other countries that have organized and effective cervical cancer screening programs. In 2010, 21,880 cases of ovarian cancer with 13,850 deaths are expected in the United States. The ovary is a complex and dynamic organ and, between the ages of approximately 11 and 50 years, is responsible for follicle maturation associated with egg maturation, ovulation, and cyclical sex steroid hormone production. These complex and linked biologic functions are coordinated through a variety of cells within the ovary, each of which possesses neoplastic potential. By far the most common and most lethal of the ovarian neoplasms arise from the ovarian epithelium found both on the surface of the ovary and in subsurface locations, known as cortical inclusion cysts, believed to be entrapped epithelium from the healing associated with prior follicle rupture during ovulation. The ovarian epithelium in good health appears as a simple epithelium, but with neoplastic transformation, it undergoes metaplastic changes into what is termed müllerian epithelium. The müllerian epithelium has a variety of subtypes each of which provide a specific phenotype of the tumor and in some cases different clinical presentations. Epithelial tumors are the most common ovarian neoplasm; they may be benign (50%), malignant (33%), or of borderline malignancy (16%). Age influences risk of malignancy; tumors in younger women are more likely benign. The most common of the ovarian epithelial malignancies are serous tumors (50%); tumors of mucinous (25%), endometrioid (15%), clear cell (5%), and transitional cell histology or Brenner tumor (1%) represent smaller proportions of epithelial ovarian tumors. In contrast, stromal tumors arise from the steroid hormone-producing cells and likewise have different phenotypes and clinical presentations largely dependent on the type and quantity of hormone production. Tumors arising in the germ cell are most similar in biology and behavior to testicular tumors in males (Chap. 96).

Tumors may also metastasize to the ovary from breast, colon, gastric, and pancreatic primaries. Bilateral ovarian masses from metastatic mucin-secreting gastrointestinal cancers are termed Krukenberg tumors.

### Ovarian Cancer of Epithelial Origin

#### Epidemiology

A female has approximately a 1 in 72 lifetime risk (1.6%) of developing ovarian cancer, with the majority of affected women developing epithelial tumors. Epithelial tumors of the ovary have a peak incidence in women in their sixties, although age at presentation can range across the extremes of adult life, with cases being reported in women in their twenties to nineties. Known risk factors that increase the chance of subsequent ovarian cancer include epidemiologic, environmental, and genetic factors such as nulliparity, use of talc agents applied to the perineum, obesity, and probably hormone replacement therapy. Protective factors include the use of oral contraceptives, multiparity, and breast-feeding. These protective factors are thought to work through suppression of ovulation and perhaps reduction of ovarian inflammation and damage associated ...

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