EXECUTIVE SUMMARY
Deaths from ovarian cancer fell worldwide between 2002 and 2012 and are predicted to continue to decline through 2020 in the United States, European Union, and, to a lesser extent, in Japan, according to newly published research. The primary reason is the use of oral contraceptives (OCs) and the long-term protection against ovarian cancer that they provide, say researchers.
- In the United States, the analysis shows a 16% drop in death rates from 5.76 per 100,000 in 2002 to 4.85 in 2012.
- An earlier collaborative reanalysis of worldwide data on combined OCs and ovarian cancer that involved 45 epidemiological studies has demonstrated that ever-users of combined OCs had reduced risk of ovarian cancer that persisted for 30 years.
Deaths from ovarian cancer fell worldwide between 2002 and 2012 and are predicted to continue to decline through 2020 in the United States, European Union, and, to a lesser extent, in Japan, according to newly published research.1 The primary reason is the use of oral contraceptives (OCs) and the long-term protection against ovarian cancer that they provide, say researchers.
Using data on deaths from ovarian cancer from 1970 to the most recent available year from the World Health Organization (WHO), scientists report that in the 28 countries of the European Union (EU), death rates fell by 10% between 2002 and 2012, from an age-standardized death rate per 100,000 women of 5.76 to 5.19. The scientists excluded Cyprus in the study, due to the unavailability of data. The decline was even greater in the United States, with a 16% drop in death rates from 5.76 per 100,000 in 2002 to 4.85 in 2012.1
In other countries, Canadian ovarian cancer death rates decreased over the same period by nearly 8% from 5.42 to 4.95. In Australia, rates fell by nearly 12% from 4.84 to 4.27, and in New Zealand, they dropped by 12% from 5.61 to 4.93 per 100,000 women. In Japan, which has had a lower rate of ovarian cancer deaths than many other countries, the death rate declined by 2% from 3.3 to 3.28 per 100,000.1
The large variations in death rates between European countries have reduced since the 1990s, when there was a threefold variation across Europe from 3.6 per 100,000 in Portugal to 9.3 in Denmark, observes Carlo LaVecchia, MD, professor in the Faculty of Medicine at the University of Milan. This finding likely is due to the more uniform use of OCs across the continent, as well as reproductive factors, such as how many children a woman has had, LaVecchia notes.
“However, there are still noticeable differences between countries such as Britain, Sweden, and Denmark, where more women started to take oral contraceptives earlier, from the 1960s onward, and countries in Eastern Europe, but also in some other western and southern European countries such as Spain, Italy, and Greece, where oral contraceptive use started much later and was less widespread,” he states. “This mixed pattern in Europe also helps to explain the difference in the size of the decrease in ovarian cancer deaths between the EU and the USA, as many American women also started to use oral contraceptives earlier.”
To perform the analysis, the research team obtained official death certification data for ovarian cancer from 1970 to 2012 or the most recent available year in each country from the WHO database, available on electronic support. Calculations for the EU were derived as a whole, looking at 28 countries as of July 2013 (minus Cyprus due to data unavailability), plus four other European countries, as well as 11 North American and South American countries and six other countries worldwide. Investigators excluded countries with fewer than 2 million inhabitants, or with fewer than 500 ovarian cancer deaths in 2005–2009.1 In addition, the researchers predicted ovarian cancer deaths and rates for 2020 for eight large countries: the United States, France, Germany, Italy, Poland, Spain, United Kingdom, and Japan, as well as the EU.
According to their projections, there will be a 15% decline in the United States and a 10% decline in the EU and Japan. Of the six European countries, only Spain reflects a slight increase, from 3.7 per 100,000 women to 3.9. This occurrence may be due to the fact that women who are middle-aged or elderly now were less likely to use OCs when they were young, says La Vecchia, because OC use started much later in Spain and was less widespread than in other European countries.
Women who use combined OCs are substantially less likely to develop epithelial ovarian cancer, notes Contraceptive Technology.2 A collaborative reanalysis of worldwide data on combined OCs and ovarian cancer involving 45 epidemiological studies has demonstrated that ever-users of combined OCs had a reduced risk of ovarian cancer that persisted for 30 years.3 Research indicates this protective effect includes the use of low-dose pills.4
The current study corroborates what has been known about the reduced incidence of ovarian cancer among OC users, and that news is great, says Susan Wysocki, WHNP-BC, FAANP, president and chief executive officer of iWomansHealth in Washington, DC, which focuses on information on women’s health issues for clinicians and consumers. “However, the study’s conclusions are based on assumptions about increases in OC use and decreases in ovarian cancer based on death certificates,” notes Wysocki. “Therefore, it does not further elucidate whether certain OC formulations or what length of use contributes to this effect.”
REFERENCES
- Malvezzi M, Carioli G, Rodriguez T, et al. Global trends and predictions in ovarian cancer mortality. Ann Oncol 2016; doi: 10.1093/annonc/mdw306.
- Nelson AL, Cwiak C. Combined oral contraceptives (COCs). In: Hatcher RA, Trussell J, Nelson AL, et al. Contraceptive Technology: 20th revised edition. New York: Ardent Media; 2011.
- Collaborative Group on Epidemiological Studies of Ovarian Cancer. Ovarian cancer and oral contraceptives: Collaborative reanalysis of data from 45 epidemiological studies including 23,257 women with ovarian cancer and 87,303 controls. Lancet 2008; 371:303-314.
- Ness RB, Grisso JA, Klapper J, et al. Risk of ovarian cancer in relation to estrogen and progestin dose and use characteristics of oral contraceptives. SHARE Study Group. Steroid Hormones and Reproductions. Am J Epidemiol 2000; 152:233-241.
