The rate in the United States, 4.85 per 100,000, puts it roughly in the middle of a list of 47 countries whose rates and trends were described recently in a study in Annals of Oncology.
The countries with the lowest ovarian cancer mortality rates are Brazil, Hong Kong and South Korea, and those with the highest are Lithuania, Ireland and Latvia. Norway, Sweden, Denmark and Finland have rates higher than the United States, as does the European Union as a whole.
Still, all European countries except Bulgaria showed declines, and the rate in the European Union fell 9.9 percent over the period.
Most of the decline, the authors write, is attributable to the use of oral contraceptives, which offer long-term protection against ovarian cancer, and to the reduced use of menopausal hormone therapy after it was found to increase rates of cancer and cardiovascular disease.
Treatment of ovarian cancer has improved, too, but not significantly enough to explain these reductions. Most advances in treatment have been limited to germ cell tumors, which account for less than 10 percent of ovarian cancers.
In the United States and Britain, where oral contraceptive use began earlier and was more widespread, rates were substantially lower among women 70 to 79 — that is, those in the first generation that widely used the birth control pill. This is significant, according to the senior author, Carlo La Vecchia, a professor of epidemiology at the University of Milan.
“Women who use oral contraceptives longer than five years when they were young,” he said, “have a substantially reduced risk of ovarian cancer even when they are in middle age and older.”
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