Three major categories account for virtually all malignant ovarian tumors. Organization of these groups is based on the anatomic structures from which the tumors originate (Fig. 36-1). Epithelial ovarian cancers account for 90 to 95 percent of malignant ovarian tumors (Chap. 35). Germ cell and sex cord-stromal ovarian tumors account for the remaining 5 to 10 percent and have unique qualities that require a special management approach (Quirk, 2005).
Origins of the three main types of ovarian tumors. (Redrawn from Chen, 2003, with permission.)
Germ cell tumors arise from the ovary's germinal elements and comprise one third of all ovarian neoplasms. The mature cystic teratoma, also called dermoid cyst, is by far the most common subtype. This accounts for 95 percent of all germ cell tumors and is clinically benign (Chap. 9). In contrast, malignant germ cell tumors comprise fewer than 5 percent of malignant ovarian cancers in Western countries and include dysgerminoma, yolk sac tumor, immature teratoma, and other less common types.
Three features typically distinguish malignant germ cell tumors from epithelial ovarian cancers. First, individuals typically present at a younger age, usually in their teens or early 20s. Second, most have stage I disease at diagnosis. Third, prognosis is excellent—even for those with advanced disease—due to exquisite tumor chemosensitivity.
Fertility-sparing surgery is the primary treatment for women seeking future pregnancy, and most will not require postoperative chemotherapy.
The age-adjusted incidence rate of malignant ovarian germ cell tumors in the United States is much lower (0.4 per 100,000 women) than that of epithelial ovarian carcinomas (15.5), but twice that of sex cord-stromal tumors (0.2) (Quirk, 2005). Smith and associates (2006) analyzed 1262 cases of malignant ovarian germ cell from 1973 to 2002 and observed that incidence rates have declined 10 percent during the past 30 years. Unlike a small proportion of epithelial ovarian carcinomas, malignant germ cell tumors are not generally considered heritable, although rare familial cases are reported (Galani, 2005; Stettner, 1999).
These tumors are the most common ovarian malignancies diagnosed during childhood and adolescence, although only 1 percent of all ovarian cancers develop in these age groups. At age 20, however, the incidence of epithelial ovarian carcinoma begins to rise and exceeds that of germ cell tumors (Young, 2003).
The signs and symptoms associated with these tumors are varied, but in general, most arise from tumor growth and the hormones they produce. Subacute abdominal pain is the presenting symptom in 85 percent of patients and reflects rapid growth of a large, unilateral tumor undergoing capsular distension, hemorrhage, or necrosis. Less commonly, cyst rupture, torsion, ...