Breast and cervical cancer in 187 countries between 1980 and 2010: a systematic analysis
Published in The Lancet, September 2011
The number of cases and deaths from breast and cervical cancer are rising in most countries, especially in the developing world where more women are dying at younger ages, according to the study Breast and cervical cancer in 187 countries between 1980 and 2010: a systematic analysis.
Researchers from IHME and the University of Queensland collected data on mortality and incidence for breast and cervical cancer, showing that while more women developed breast or cervical cancer in 2010 than in 1980, the probability that women will die from either disease has decreased.
Coinciding with the study release, IHME published a report, The Challenge Ahead: Progress and Setbacks in Breast and Cervical Cancer, which provides global, regional, and country data for cases, deaths, and risks over the past three decades. The work was funded by Susan G. Komen for the Cure.
Breast and cervical cancer are important reproductive health problems for women, and programs to address the burden of these diseases have gained attention in the discussions leading up to the United Nations High-level Meeting on Non-communicable Diseases. Evidence shows that screening and treatment for breast cancer are effective, as is human papillomavirus vaccination for cervical cancer. Because of the importance of these diseases and the potential for effective treatment and prevention, it is critical to monitor trends in the mortality and incidence of breast and cervical cancer, by country and over time.
Overall, the number of cases and deaths from breast and cervical cancer are rising in most countries, especially in the developing world where more women are dying at younger ages.
Global breast cancer incidence increased from 641,000 cases in 1980 to 1,643,000 cases in 2010, an annual rate of increase of 3.1%. More than two-thirds of cases of breast cancer in 2010 were in women aged 50 years and older, most of which were in developed countries. For women between the ages of 15 and 49, there were twice as many breast cancer cases in developing countries than in developed countries. In 2010, 425,000 women died from breast cancer, of whom 68,000 were between the ages of 15 and 49 in developing countries.
Global cervical cancer incidence increased from 378,000 cases in 1980 to 454,000 cases in 2010, an annual rate of increase of 0.6%. New cases of cervical cancer occur more often in developing countries than in developed countries in all age groups. In 2010, 200,000 women died from the disease, of whom 46,000 were between the ages of 15 and 49 in developing countries.
Researchers collected data on mortality and incidence from cancer registries, vital registration systems, and verbal autopsies between 1980 and 2010. They modeled the mortality-to-incidence (MI) ratio, a measure of the women with cancer who die annually, and supplemented vital registration and verbal autopsy data with incidence multiplied by the MI ratio to yield a comprehensive database of mortality rates.
While systematic attempts to assess incidence and mortality for cancers have been undertaken by the International Agency for Research on Cancer (IARC) and released through the GLOBOCAN website, these efforts have limitations. Differences between the methods used in this study and those used by IARC include:
- IHME researchers based their estimates on additional sources of data, especially for cancer deaths, including the use of verbal autopsy data in countries that lack vital registration systems.
- Many cancer deaths are inaccurately coded or ill-defined by agencies collecting the data, and IHME methods fix the coding and assign the deaths to the appropriate categories.
- To generate the MI ratio, IHME improved on previous methods by factoring in age, country, and year.
- While IHME uses one approach in every country, GLOBOCAN data are based on 26 different approaches for different groups of countries.
- Many of the approaches used for estimating mortality in the GLOBOCAN data rely on trends observed in Nordic countries, and IHME researchers believe that relying on a limited number of countries leads to an overestimation of MI ratios in many developing countries.
The authors suggest that increases in the absolute number of cases and deaths from breast and cervical cancer may be due to the interaction of the following factors: rising population numbers in women of at-risk age, aging of the population, and changes in age-specific incidence and death rates. As a result of the rising numbers of deaths from breast and cervical cancer and the decreasing numbers from maternal mortality, more deaths occur worldwide from breast and cervical cancer than from maternal mortality. Based on current trends, breast and cervical cancer will likely approach maternal causes of death in women of reproductive age in developing countries within the next two decades.
The researchers conclude that better surveillance systems are needed to monitor the trends in breast and cervical cancer incidence and mortality. In addition, more policy attention is needed to strengthen established health-system responses to reduce breast and cervical cancer, especially in developing countries.
Citation: Forouzanfar MH, Foreman KJ, Delossantos AM, Lozano R, Lopez AD, Murray CJL, Naghavi M. Breast and cervical cancer in 187 countries between 1980 and 2010: a systematic analysis. The Lancet. 2011; DOI:10.1016/S0140-6736(11)61351-2.
Data and Methods
Figure 1. Change in the lifetime risk of death from breast cancer, 1980 and 2010 (1MB PDF)
Figure 2. Breast cancer cases in developed and developing countries by age, 1980 and 2010 (73KB PDF)
Table 1. Breast cancer cases and deaths in developing and developed countries, 1980 and 2010 (73KB PDF)
Table 2. Cervical cancer cases and deaths in developing and developed countries, 1980 and 2010 (73KB PDF)
Data for download. Breast and cervical cancer incidence and mortalty by age and country, 1980 and 2010 (95KB xls)
To download further datasets, including the underlying data for this research, visit our Global Health Data Exchange (GHDx). After providing some basic registration information, you will have access to additional datasets and detailed information about the data used in this research. The GHDx includes data records with information on more than 200 countries.
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In September 2011, IHME published in The Lancet global estimates for breast and cervical cancer: Breast and cervical cancer in 187 countries between 1980 and 2010: a systematic analysis. The new estimates differed from estimates available from the International Agency for Research on Cancer through the GLOBOCAN website.
- We based our estimates on additional data sources, especially for cancer deaths. For example, in some countries that lack vital registration data, we were able to use data from verbal autopsy studies, which gather information from relatives about how a family member died. Even in countries where rich data sources are available, IARC used modeled mortality estimates from the World Health Organization. For cervical cancer deaths in India, for example, the IARC approach yields a much higher number of deaths than the IHME approach.
- In both vital registration systems and cancer registries, many cancer deaths are inaccurately coded or ill-defined by the agencies collecting the data. Using methodological tools designed at IHME, we fixed the coding and assigned the deaths to the appropriate categories.
- To generate the mortality-to-incidence (MI) ratio, a key measure for the number of women with cancer who die annually, we improved on previous methods by factoring in age, country, and year. We have found that our estimates are in sync with data from cancer registries.
- We use one approach for estimating mortality data in 187 countries. GLOBOCAN data are based on 26 different approaches for different groups of countries. The approach used for Saudi Arabia and South Africa, for example, is different from the one used for Vietnam and China.
- Many of the approaches used for estimating mortality in the GLOBOCAN data rely on trends observed in Nordic countries. We believe relying on such a limited number of countries leads to an overestimation of MI ratios in many developing countries, particularly for breast cancer.
- A detailed discussion of our methods can be found in the Web Appendix with the journal article.