The number of new cases of breast cancer diagnosed worldwide has risen dramatically from about 640,000 in 1980 to 1.6 million in 2010. During the same period, cervical cancer incidence and death rates have been decreasing, but the disease still killed 200,000 women in 2010, according to the first global estimates published Sept. 14 in The Lancet. The report shows that, in 2010, 51 percent of the 1.6 million new cases of breast cancer and 76 percent of the 425,000 new cases of cervical cancer occurred in developing countries.
One of the most “surprising” findings, according to the authors, was the sharp rise in women of reproductive age in developing countries who are being diagnosed with and dying from breast and cervical cancer, suggesting that these diseases should be given similar global priority to maternal mortality.
"If the trends of the past three decades were to continue during the next 15 years, the ratio of maternal deaths to breast and cervical cancer deaths in developing countries in the reproductive age group will decrease from 2.3 to 1.3," the study’s corresponding author, Christopher J. L. Murray, MD, DPhil, from the Institute for Health Metrics and Evaluation and the professor of global health at the University of Washington in Seattle, said in a statement.
Until now, assessments of breast and cervical cancer have used up to 26 different combinations of methods to calculate the number of new breast and cervical cancer cases and deaths, and have not generated uncertainty intervals to provide guidance on the robustness of a country's estimates.
This study provides comparable data collected and modeled from more than 300 cancer registries and cause-of-death offices to develop yearly age-specific assessments of breast and cervical cancer in 187 countries from 1980 to 2010, according to the study authors. The researchers also used a standardized method that can be replicated to generate yearly estimates for these cancers in each country.
Over the past 30 years, the incidence of breast cancer has increased in all regions of the world at an annual rate of 3.1 percent. The report identified twice as many breast cancer cases among women aged 15 years or older in developing countries compared with developed countries.
In contrast, the rise in deaths from breast cancer globally has been slower than the rise in cases, increasing from about 250,000 in 1980 to 425,000 in 2010, possibly reflecting the effectiveness of early detection and treatment advances in developed countries.
Since 1980, new cases and deaths from cervical cancer have increased mainly in South and East Asia, Latin America and Africa, but have declined substantially in high-income countries, particularly where widespread screening is available. However, the disease still killed 200,000 women around the world in 2010, of whom 46,000 were of reproductive age in developing countries.
The analysis also showed that breast cancer survival rates varied widely across regions and countries.
"The complexity of the pattern for breast cancer and to a lesser extent for cervical cancer draws attention to the importance of building better surveillance systems," the authors wrote. "It also draws attention to the importance of the development of national control strategies for both cancers that show local epidemiological patterns and trends."
Murray et al concluded that these important cancers are to an extent preventable through measures such as screening, human papillomavirus vaccination and tobacco control: "In view of the potential for effective health system responses … more policy attention is needed to strengthen established health system responses to reduce breast and cervical cancer, especially in developing countries."
In the accompanying commentary, Jan W. Coebergh, MD, PhD, of the Erasmus University Medical Centre in Rotterdam, The Netherlands, emphasized the importance of increasing investment in surveillance: "Investments towards improvement in these processes would be a minor financial burden for those responsible for public health, clinical care in oncology and the various paymasters for healthcare. Improved cancer surveillance systems would also allow a detailed view of the quality of evolving clinical care, not only in different health settings and countries but in respect of the various emerging and declining epidemics of individual cancers."