Breast cancer is by far the primary cancer site in women.
Washington D.C.: Breast cancer mortality rates of women, especially under the age of 50, continue to decline in many nations, due to advances in detection and treatment over the past few decades, finds a new study.
The study was presented at the 2016 San Antonio Breast Cancer Symposium.
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 percent decline.
"Breast cancer is by far the primary cancer site in women and, worldwide, represents a quarter of all cancers in women," said lead study author Cecile Pizot from the International Prevention Research Institute in Lyon, France.
"Comparing mortality trends between countries helps identify which health care systems have been the most efficient at reducing breast cancer mortality," Pizot added.
In this study, researchers extracted information on breast cancer deaths from the World Health Organization database and calculated mortality rates over the years 1987-2013, stratifying results according to age groups. Pizot said this trend was to be expected, due to advances in detection and treatment over the past few decades.
Latin American nations experienced scattered increases in mortality; for example, Brazil and Colombia saw mortality rates increase in women of all age groups, while in Argentina and Chile mortality rates decreased in all women.
"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."
In the United States, the mortality rate declined 42 percent, from 22 deaths per 100,000 women in 1987-1989 to 14 deaths per 100,000 women in 2011-2013. Pizot said mortality rates declined for all age groups -- by 50 percent for women under 50; by 44 percent for women between 50 and 69 years old; and by 31 percent for women 70 or older.
Globally, mortality rates declined more for women under 50 than for women over 50. Pizot said 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.