Epidemiology of hydatidiform mole and choriocarcinoma

Epidemiol Rev. 1984:6:52-75. doi: 10.1093/oxfordjournals.epirev.a036275.

Abstract

PIP: Hydatidiform mole, with a relative risk for choriocarcinoma of 2000-4000, may be 1 of the largest single risk factors for any disease. This review examines the incidence, distribution, and major etiologic hypotheses for the 2 diseases. It is unclear whether hydatidiform mole and choriocarcinoma, both diseases of the trophoblast, are different phases of a single disease process or discrete entities, although hydatidiform mole itself may represent at least 2 disease processes: complete, or classic, in which the conceptus lacks a fetus, and partial, which coexists with a fetus. Painless vaginal bleeding, a uterus large for dates, hyperemesis, toxemia prior to 20 weeks, and absent fetal parts and heart tones are among diagnostic critieria. Marked difference in incidence of hydatidiform mole among countries is widely acknowledged, with reports ranging from 11.5/1000 deliveries in Indonesia to less than 1/1000 deliveries in the US. Incidence appears much higher in Asia, Africa, and Central America than in the US, Europe, or Australia. Maternal age is the most consistent risk factor for hydatidiform mole in every region and ethnic group in which it has been studied, with most studies showing a significant increase in risk in women delivering above age 35 and a further 10-fold increase beyond age 40. Data on incidence by pregnancy history are inconclusive, although a history of twin pregnancies may both precede and follow hydatidiform mole. It is not known whether observed variations in mole incidence reflect true population differences or whether they are artifacts due to different referral patterns and diagnostic criteria or selection bias. Several possible factors in the etiology of hydatidiform mole have been studied: socioeconomic and nutritional factors, environmental agents, parasites, infection, consanguinity, blood types, missed abortion, and genetic factors. Although a genetic role in the epidemiology of hydatidiform mole is now certain, very little is known about environmental factors that may increase the risk of defective ova or about conceiving genotypes that are precursors to mole. Future epidemiologic studies must classify mole as either complete or partial, particularly since complete moles appear to have the high risk of subsequent choriocarcinoma and metastasis. Invasive mole and choriocarcinoma may be difficult to diagnose except in patients with prior hydatidiform mole, who face approximately a 10% risk of malignant sequelae. About 60% of choriocarcinomas are not preceded by a clinically recognized molar pregnancy. In recent years surgery and chemotherapy have achieved a nearly 100% cure rate. Choriocarcinoma incidence appears to vary widely by geographic region and racial group. Data on etiologic factors for choriocarcinoma are lacking, largely because of difficulties in studying such a rare tumor. Maternal age and history of hydatidiform mole are the only 2 established risk factors, although studies have speculated on risks of oral contraceptives and other exogenous hormones, consanguinity, blood groups, and other factors.

Publication types

  • Review

MeSH terms

  • Abortion, Missed / complications
  • Adolescent
  • Adult
  • Blood Group Antigens
  • Choriocarcinoma / epidemiology*
  • Choriocarcinoma / etiology
  • Choriocarcinoma / genetics
  • Choriocarcinoma / mortality
  • Consanguinity
  • Contraceptives, Oral / adverse effects
  • Environmental Exposure
  • Epidemiologic Methods
  • Female
  • HLA Antigens
  • Helminthiasis / complications
  • Humans
  • Hydatidiform Mole / epidemiology*
  • Hydatidiform Mole / etiology
  • Hydatidiform Mole / genetics
  • Infections / complications*
  • Karyotyping
  • Maternal Age
  • Parity
  • Pregnancy
  • Racial Groups
  • Seasons
  • Sex Chromatin / analysis
  • Uterine Neoplasms / epidemiology*
  • Uterine Neoplasms / etiology
  • Uterine Neoplasms / genetics
  • Uterine Neoplasms / mortality

Substances

  • Blood Group Antigens
  • Contraceptives, Oral
  • HLA Antigens