The number of cases and deaths from breast and cervical cancer is rising in most countries across the world, especially in poorer nations where more women are dying at younger ages, according to a global study of the diseases.
Researchers from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington found breast cancer cases more than doubled around the world in just three decades, from 641,000 cases in 1980 to 1.6 million cases in 2010 -- a pace that far exceeds global population growth.
During the same period, deaths from breast cancer rose from 250,000 a year to 425,000 a year -- a much slower increase, suggesting that screening and treatment programs now common in wealthier countries are having a positive impact.
The number of cervical cancer cases rose from 378,000 cases in 1980 to 454,000 in 2010, and deaths from cervical cancer rose at almost the same pace as cases, according to the study published in The Lancet medical journal on Thursday.
"Women in high-income countries like the United States and the United Kingdom are benefiting from early cancer screenings, drug therapies, and vaccines," said Rafael Lozano, a professor of global health at IHME who worked on the study. "We are seeing the burden of breast and cervical cancer shifting to low-income countries in Africa and Asia."
He said this was one of the early signs of the emerging threat of so-called non-communicable or chronic diseases, in developing countries. "Everyone has been talking about that threat. Now the trend is clear," he said.
The study found that 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 in countries where widespread screening is available.
However, the disease still killed 200,000 women around the world in 2010, of whom 46,000 were from developing countries and were of reproductive age.
The researchers said the findings added urgency to calls from public health experts to world leaders to make cancer screening, treatment, and education a priority in poor nations.
The United Nations is holding a high-level meeting dedicated to chronic diseases such as cancer, heart disease, lung disease and diabetes in New York on September 19-20.
"If more women are developing breast and cervical cancer during their reproductive years, this adds more pressure on families and societies already suffering from high rates of infectious disease and child mortality," said Mohammad Forouzanfar of the IHME, who led the study.
Breast and cervical screening programs have been in place in many rich countries for several decades, designed to catch cancers early and maximize the potential for effective treatment.
Many effective breast cancer treatments are also available to women in the rich world. More recently, national immunization programs using new vaccines from drugmakers Merck and GlaxoSmithKline have been launched to protect girls from the human papillomavirus (HPV) that causes almost all cervical cancers.
Partly as a result of these rich-world benefits, the study found that while in 1980, 65 percent of all breast cancer cases were in developed countries, by 2010, that share had shrunk to less than half. Some poorer countries saw a rise in breast cancer cases of more than 7.5 percent a year over the 30 year period studied -- more than twice the global rate.
The risk of cervical cancer is much higher in developing countries than in developed ones.
Overall, 76 percent of new cervical cancer cases are in developing regions. Sub-Saharan Africa has 22 percent of all cervical cancer cases worldwide.