ORAL-CONTRACEPTIVES AND PRIMARY LIVER-CANCER - TEMPORAL TRENDS IN 3 COUNTRIES

Objective: To determine if vital statistics support a temporal associa tion between the introduction of oral contraceptives (OC) and the inci dence of, and mortality from, primary liver cancer in three countries from different regions of the world. Methods: We used Cancer Incidence in Five Continents, volumes I-VI, for incidence data on primary liver cancer in the United States and Japan. The Centre for Epidemiology in Stockholm provided the incidence data for Sweden. We obtained mortali ty data for the U.S. from Vital Statistics of the United States, for J apan from The World Health Statistics Annual, and for Sweden from Swed ish government sources. We compiled data on the prevalence of OC use i n all three countries from multiple sources, including the National Su rvey of Family Growth, The population Council, and original articles. Results: Despite several hundred million woman-years of exposure to OC s, primary liver cancer incidence and mortality rates among women have not changed substantially in the United States. In Sweden, another co untry with extensive OC use, the primary liver cancer incidence trends in women paralleled those of men. The incidence of, and mortality rat e from, primary liver cancer is gradually rising in Japan, where OC us e has been negligible. Conclusion: Population-based data from three in dustrialized countries with very different patterns of oral contracept ive use provide no support for a measurable effect of OCs on primary l iver cancer. Although case-control studies from developed countries ha ve suggested an increase in risk, if such an effect does exist, the pu blic health impact appears to be negligible. Copyright (C) 1996 by The American College of Obstetricians and Gynecologists.