Cancer rates decline in many high-income countries, but rise in lower-income countries
Improved screening and detection efforts, combined with decreases in risk factors like smoking, have reduced the incidence and mortality rates from several common types of cancer in many high-income countries. However, many low-and middle-income countries have seen cancer rates rise, partially due to increases in risk factors that are typical of Western countries.
The study was published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research
Worldwide, an estimated 14.1 million new cancer cases and 8.2 million cancer deaths occurred in 2012, the authors said. Cancer is a leading cause of death worldwide in countries of all income levels, and the number of cancer cases and deaths is expected to grow rapidly as populations grow, age, and adopt lifestyle behaviors that increase cancer risk.
Torre and colleagues analyzed incidence and mortality data for the years 2003-2007 from the International Agency for Research on Cancer (IARC) CancerMondial database, which includes incidence data through 2007 from Cancer Incidence in Five Continents, a collaboration between the IARC and the International Association of Cancer Registries, and mortality data through 2012 from the WHO Cancer Mortality database. Study data reflect 50 countries selected to represent various regions of the world.
The authors noted developments across eight major kinds of cancer, which account for 60 percent of total global cases and deaths. The report detailed trends in breast, prostate, colorectal, lung, esophageal, stomach, liver and cervical cancers. The incidence and mortality of many of these cancers have decreased in high-income countries, but risen in low-and middle-income countries due to factors that may include lifestyle changes and lack of appropriate screening or prevention measures.
"This study gives us important clues about the epidemiology of cancer and gives us some ideas about what we could further investigate to improve global public health," Torre said.
Torre said that the most significant limitation of the study was the variation in reporting standards from one country to the next. For example, she said some nations do not require deaths to be registered, so the mortality data may not be fully representative. Also, data in many countries were collected only in urban centers, which means that cancer incidence and mortality across a whole country's population may not be accurately reflected.