This story is part of a partnership between MedPage Today and VICE News.
As wealthy countries have got better at detecting and treating cancer, as well as reducing certain risk factors, rates of the disease have significantly reduced since the early 2000s — but in low- and middle-income countries the opposite is happening.
A new study in the medical journal Cancer, Epidemiology, Biomarkers and Prevention has documented a global shift in the disease, finding that while developed countries still have the highest incidence rates of cancer overall, these rates are largely plateauing or decreasing. Meanwhile, some developing countries are catching up, as people live longer and their lifestyles become more westernized.
"They are developing, and that comes with many great things," said Lindsey Torre, MSPH, who along with colleagues at the American Cancer Society looked at more than a decade of cancer and mortality data from 50 countries for the study. "People have more income and more options. It also means people aren't as active as they used to be. They might be taking transportation when they used to walk… With extra income, they may start smoking, drinking more alcohol. All those are cancer risk factors."
Torre and her co-authors noted that they found a wide variation in the types of cancers that were most frequently diagnosed in each country. For instance, breast and cervical cancers were the most commonly diagnosed cancers among people in most of Asia, but lung cancer was the most frequently diagnosed cancer in China and North Korea. Torre said the study also illustrated a mysterious "esophageal cancer belt" between Iran and China.
This is the first report of its kind on cancer trends around the world, said Dr. Neal Meropol, chief of hematology and oncology at UH Case Medical Center in Cleveland, Ohio. Meropol was not involved in the study.
"Those of us who are privileged enough to live and work in high income countries have a very skewed perception on global health issues," he said. "My life in the United States, my experience with cancer research and patient care in the United States represents only a small slice of a global problem. And it behooves all of us to have a broader view and a sense of responsibility to address issues that exist for people in less fortunate circumstances."
For instance, Meropol said people in developed countries take for granted cancer screening and prevention strategies even though they lead to reduced cancer incidence and better patient survival rates.
The study is important because it shows that many of the cancers in low and middle income countries are preventable, Torre said. For example, these countries could benefit from cancer screening programs as well as programs to keep teens from smoking cigarettes. They could also benefit from more widespread use of the HPV vaccine, which prevents the virus that leads to cervical cancer.
"They may not have resources to deal with the cancer burden in these countries," Torre said. "A study like this is important not only to bring to their attention to it, but all of the attention of the international community."
But the study had limitations, the authors wrote. Although data in high income countries is considered complete and reliable, the middle- and low- income countries didn't always have high quality data. In some cases, that may have led to underestimation of cancer cases and deaths, Torre said. In others, it could have led to overestimation.
Still, the study should not be disregarded because the data isn't perfect, said Meira Epplein, PhD, a cancer epidemiologist at Vanderbilt University School of Medicine who was not involved in the study.
Cancer was once thought of as a disease that mostly affected the developed world because it was a disease of old age, Epplein said. Then, it seemed the developing world was only plagued by cancers caused by infections, such as cervical, liver and stomach cancers.
But that's all changing, and this report helps to quantify it, she said.
"The paper is trying to give us a heads up about these other cancers rising in the developing world as well as to think about what can we do as far as prevention," she said.