Breast cancer mortality declined in 39 out of 47 countries, including the United States and most developed European nations. [Oakozhan/Getty Images]
Breast cancer mortality declined in 39 out of 47 countries, including the United States and most developed European nations. [Oakozhan/Getty Images]

New study results presented recently at the 2016 San Antonio Breast Cancer Symposium are cause for celebration as many nations around the world continue to show significant declines in breast cancer mortality rates. However, those celebrations should be tempered with the knowledge that the positive trends seen in 47 countries are counterbalanced by some significant disparities, principally in South Korea and some Latin American nations.  

“Breast cancer is by far the primary cancer site in women and, worldwide, represents a quarter of all cancers in women,” noted the study's lead author, Cécile Pizot, a biostatistician at the International Prevention Research Institute in Lyon, France. “Comparing mortality trends between countries helps identify which healthcare systems have been the most efficient at reducing breast cancer mortality.”

For the current study, the investigators were able to extract information on breast cancer deaths from the World Health Organization database and calculate mortality rates during 1987–2013—stratifying results according to age groups.

What the researchers found was that overall, breast cancer mortality declined in 39 out of 47 countries, including the United States and most developed European nations. England and Wales had the sharpest drop in mortality, with a 46% decline. The scientists surmised that this general trend was not wholly unexpected, due to advances in detection and treatment over the past few decades.

However, Latin American nations experienced scattered increases in mortality—for instance, Brazil and Colombia saw mortality rates increase in women of all age groups, while in Argentina and Chile mortality rates decreased in all women.

Yet, South Korea had the most dramatic increase in breast cancer mortality, with an 83% increase overall and higher mortality in every age group. However, the breast cancer mortality rate is still lower than the rate in the United States (5.3 per 100,000 women in South Korea compared with 14 per 100,000 women in the United States in the 2011–2013 period).

“South Korea has experienced major societal changes since the 1950s and quickly evolved from an agricultural, developing country to a highly industrialized and Westernized country,” Pizot said. “Such quick changes might explain the considerable shift in cancer mortality.”

Additional highlights from the study:

  • In the United States, the mortality rate declined 42%, from 22 deaths per 100,000 women in 1987–1989 to 14 deaths per 100,000 women in 2011–2013. Mortality rates declined for all age groups—by 50% for women under 50; by 44% for women between 50 and 69 years old; and by 31% for women 70 or older.
  • Globally, mortality rates declined more for women under 50 than for women over 50. The investigators believe that this reflects the fact that younger women tend to receive more intense treatments (such as longer courses of chemotherapy), which prolong their survival and may defer breast cancer death in older ages.
  • The role of breast cancer screening was not clearly apparent in mortality trends. The study revealed several cases where nations with similar geographic locations and socioeconomic status experienced similar trends, no matter whether the country has used mammography screening since the 1980s or whether mammography was introduced in 2005 or later.

“This finding underlines the difficulty of isolating a single, common factor that would have a significant influence on mortality trends,” Pizot said. “Differences in healthcare systems and patient management could explain discrepancies in mortality reduction between similar countries. However, there is at present little data comparing the management of breast cancer patients across countries.”

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