Epidemiology of hydatidiform mole in Finland, 1975 to 2001

Purpose: Broad variations in the incidence of gestational trophoblastic diseases have been reported in different parts of the world. Recent time trends in the incidence of hydatidiform mole in Western countries have not been elucidated. We studied the epidemiology of hydatidiform mole in Finland over a period of 27 years. Methods: Women reported to have hydatidiform mole from 1975-2001 were identified from the National Research and Development Center for Welfare and Health. Women with choriocarcinoma were identified from the Finnish Cancer Registry. Results: We identified 1,659 cases of hydatidiform mole between 1975 and 2001. This gives an incidence of 73/10(6) women or 984/10(6) deliveries. The overall incidence remained fairly constant over the study period. The incidence was higher in women below 20 years and above 39 years than in women in the other age groups. Forty-nine percent of choriocarcinomas identified during the study period were associated with a preceding hydatidiform mole. The risk of choriocarcinoma after a hydatidiform mole was 2.2%. Conclusion: The incidence of hydatidiform mole in Finland follows the same patterns as in other Western countries. The incidence has not changed considerably in recent decades.