Gestational trophoblastic disease refers to a spectrum of interrelated but histologically distinct tumors originating from the placenta (Table 37-1). These diseases are characterized by a reliable tumor marker, which is the β-subunit of human chorionic gonadotropin (β-hCG), and have varying tendencies toward local invasion and spread.
Table 37-1. Modified World Health Organization Classification of Gestational Trophoblastic Disease |Favorite Table|Download (.pdf)
Table 37-1. Modified World Health Organization Classification of Gestational Trophoblastic Disease
Placental site trophoblastic tumor
Epithelioid trophoblastic tumor
Gestational trophoblastic neoplasia (GTN) refers to the subset of gestational trophoblastic disease that develops malignant sequelae. These tumors require formal staging and typically respond favorably to chemotherapy. Most commonly, GTN develops after a molar pregnancy, but may follow any gestation.
The prognosis for most cases of GTN is excellent, and patients are routinely cured even in the presence of widespread metastases. The outlook for preservation of fertility and for successful subsequent pregnancy outcomes is equally bright (Garrett, 2008). Accordingly, although gestational trophoblastic disease is uncommon, because the opportunity for cure is great, clinicians should be familiar with its presentation, diagnosis, and management.
The incidence of gestational trophoblastic disease has remained fairly constant at approximately 1 to 2 per 1000 deliveries in North America and Europe (Drake, 2006; Loukovaara, 2005; Savage, 2010; Smith, 2003). A similar frequency has been observed in South Africa and Turkey (Moodley, 2003; Ozalp, 2003). Although historically higher incidence rates have been reported in parts of Asia, this may have largely reflected discrepancies between population-based and hospital-based data collection. For example, a South Korean population-based study noted a drop in the incidence from 40 per 1000 deliveries to 2 per 1000 that was coincident with refinement in disease terminology and classification (Kim, 2004). Similarly, hospital-based studies in Japan and Singapore have shown a decreased incidence (Chong, 1999; Matsui, 2003). Improved socioeconomic conditions and dietary changes may be partly responsible as well. Some ethnic groups, however, appear to be at higher risk of developing gestational trophoblastic disease. Hispanics and Native Americans living in the United States reportedly have an increased incidence, as do certain population groups living in Southeast Asia (Drake, 2006; Smith, 2003; Tham, 2003).
Maternal age at the upper and lower extremes has been found to carry a higher risk of gestational trophoblastic disease (Altman, 2008; Loukovaara, 2005; Tham, 2003). This association is much greater for complete moles, whereas the risk of partial molar pregnancy varies relatively little with age. Moreover, compared with the risk of those with maternal age of 15 years or younger, the degree ...